As plague after plague befalls the Egyptians, Pharaoh remains steadfast in his refusal to release the Israelites. Finally, the last plague, the death of the first born, beats Pharaoh into submission, and the Jews are set free. This last and most terrible of the ten plagues, however, was the first one foretold to Moshe:
And God said to Moshe, 'When you set out to return to Egypt, see all those wonders which I have put in your hand, and perform them before Pharaoh; but I will harden his heart, and he will not let the people go. And you shall say to Pharaoh, "Thus said the Eternal God: ‘Israel is my son, my firstborn; And I say to you, Let my son go, that he may serve Me; and if you refuse to let him go, behold, I will slay your son, your firstborn.’"(4:21-23)
For this reason, when the time finally comes, there is no need for God to inform Moshe what the final plague will be, because Moshe already knows.He has been ready and waiting for this plague, and God simply says that “one more plague” will be visited upon Egypt:
And God said to Moshe, 'I bring one plague more upon Pharaoh, and upon Egypt; afterwards he will let you go from here; when he shall let you go, he shall certainly thrust you out from here altogether. (11:1)
And Moshe said, 'Thus said the Eternal God, ‘About midnight I will go out into the midst of Egypt;And every firstborn in the land of Egypt shall die, from the firstborn of Pharaoh that sits on his throne to the firstborn of the maidservant who is behind the mill; and all the firstborn of beasts.And there shall be a great cry throughout all the land of Egypt, such as there never was, nor shall there ever be again. (11:4-6)
According to tradition, this plague was the most severe.The fact that this is the one of which Moshe was told at the very beginning, even before her returned to Egypt to confront Pharaoh, indicates that this plague was one of the objectives Moshe was sent to achieve, one of the crucial elements of the Exodus itself.The question is, why?
The answer may lie much earlier in the text of the Torah, in the promise God made to Avraham in the Book of Bereishit- in a covenant known as the brit bein habitarim:
And when the sun was going down, a deep sleep fell upon Avram; and, lo, a fear of great darkness fell upon him. And He said to Avram, 'Know for a certainty that your descendants will be strangers in a land that is not theirs, and shall serve the (masters of that land), who will afflict them four hundred years; And also that nation, whom they shall serve, will I judge; and afterward shall they come out with great wealth.' (Bereishit 15:12-14)
There will be a time of servitude, but the nation that afflicts the descendants of Avraham will be judged for their misdeeds. The mode of judgement, however, remains unclear.
This idea is echoed in the revelation Moshe received at the burning bush:
And I will stretch out my hand, and strike Egypt with all my wonders which I will do in its midst; and after that he will send you away. And I will give this people favor in the sight of the Egyptians; and it shall come to pass, that, when you go, you shall not go emptyhanded. Every woman shall borrow from her neighbor, and from the one who resides in her house, jewels of silver, and jewels of gold, and garments; and you shall put them upon your sons and upon your daughters; and you shall plunder Egypt. (3:20-22)
Like Avraham before him, Moshe is told that there will judgement of the oppressing nation, and great wealth for the Jews, as the servitude comes to an end. Ramban explains that God promised Avrahamthat the judgement would determine whether the oppressing nation had followed the divine plan of enslaving the Jewish People, or if they had gone "beyond the call of duty" by behaving cruelly.
According to this opinion, ostensibly the Egyptians could have been judged, and found innocent; Bereishit neither promises nor anticipates any punishment for the enslaving nation. The promise God made to Avraham could have been fulfilled if the enslavers had treated the Jews humanely, and eventually set their erstwhile slaves free after paying them a decent wage for their years of hard labor. But this is not the path the Egyptians chose. They volunteered for the job, and assumed the role of oppressors with enthusiasm, with zeal, with a murderous vengeance. When God forged the covenant with Avraham, He enumerated enslavement in a foreign land; The role of enslaver was not pre-ordained, it was chosen – and genocide was never part of the promise. When the Egyptians began casting the male Jewish children into the Nile, they were judged, found guilty of unnecessary cruelty and infanticide, and sentenced to endure plagues - and the death of their own sons:
"This month shall be unto you" (12:2). It is written: "And you shall say unto Pharaoh: 'Thus said the Almighty God: Israel is My son, My firstborn. And I say to you: Let My son go, that he may serve Me; and you have refused to let him go. Behold, I will slay your son, your firstborn (4:22,23). Exalted be the name of the Holy One, blessed be He, who foretells the end at the beginning. In connection with Avraham it says: ’And also that nation, whom they shall serve, will I judge.‘ (Bereishit 15:14) What was the judgment? The slaying of the firstborn, which was called a plague, as it says: Yet one plague more (11:1). What is the meaning of: ‘I will judge’? God said: ‘I will punish them with the slaying of the firstborn,’ for it says: ’Behold, I will smite your son, even your firstborn.’ (Midrash Rabbah - Exodus 15:27)
The plague of the firstborn stands out; above all the other plagues, it is Divine retribution against Pharaoh and all of Egypt. In fact, another Midrash teaches that it was to be theplague – the onlyplague. The others were merely God’s response to Pharaoh's insolence:
When God at first sought to bring the plagues upon Egypt, He intended to commence with the plague of the firstborn, for it says: 'Behold, I will slay your son, your firstborn (Shmot 4:23). Pharaoh then retorted: ’Who is God that I should hearken unto His voice’ (5:2). Then God said: ‘If I bring the plague of firstborn upon him at the outset, he will send them out at once; no, I will bring other plagues upon him first, by this means will I bring them all. (Midrash Rabbah 18:5)
In this Midrash, as in those we read earlier, the plague of the firstborn was the central vehicle of retribution; the other plagues were afterthoughts. At face value, we might say that this final plague was the worst of all because it resulted in death, while the preceding plagues brought various degrees of discomfort or pain. However, there may have been an additional element that made the death of the firstborn particularly severe for the Egyptians.
Needless to say, the death of any child is horrific. The logic dictated by God is clearly understood: If you are callous to my children, I will wreak vengeance on your children. This, though, does not explain why specifically the firstborn are singled out. A number of Midrashim shed light on this question.
מכילתא דרבי ישמעאל בא - מסכתא דפסחא פרשה יג
ותחזק מצרים על העם מגיד שהיו טורדין אותם לצאת בבהלה: כי אמרו כלנו מתים אמרו לא כגזרת משה משה אמר ומת כל בכור בארץ מצרים והיו סבורין שכל מי שיש לו ד' או ה' בנים אין מת אלא הבכור שבהם והם לא היו יודעין שנשותיהן חשודות בעריות וכולן בכורים מרווקים אחרים הן עשו בסתר והב"ה פרסם אותם.
And the Egyptians urged the people (to leave Egypt) in haste; for they said, 'We will all die.’(12:33) They said, 'This is not what Moshe had decreed. Moshe said only the firstborn of Egypt will die.' They thought whoever had four or five children would only lose the first. They didn't know that their wives were immoral, and each of "their" children were actually fathered by different young men. They had transgressed secretly, yet God caused it to become known. (Michilta Bo)
Unbeknownst to the Egyptians, there were actually many "firstborns" in each family. The humiliation that they suffered must have been tremendous. While this Midrash gives us further insight as to why Egyptian society was destroyed, it does not completely satisfy as an explanation for the specificity of the tenth plague: There is certain poetic justice in the eradication of a society that displays such severe moral decay, but why were the firstborn targeted?
In order to fully understand this plague, we must appreciate the hierarchic structure of Egyptian civilization. This was a society built on primogeniture; the firstborn had absolute power within the family unit. Pharaoh was the firstborn of the firstborn of the firstborn. His place in the family structure entitled him to his birthright and gave him his power. The visual representation of this concept is a pyramid.
The attack against the firstborn was a powerful polemic against the underpinnings of Egyptian culture: The eldest son ruled the younger siblings, making slavery a crucial foundation of the entire Egyptian system: It gave the lower classes someone of an even lowlier status to control and dominate. Pharaoh, as firstborn of the firstborn, ruled all of Egypt. The other firstborn sons controlled the non-firstborn Egyptians, and these "ordinary" Egyptians lorded over the taskmasters, who in turn dominated the slaves.
In his commentary to Shmot, The Netziv (Naftali Zvi Yehuda Berlin) explains this idea through a fascinating observation concerning the song the Israelites sang as they witnessed the splitting of the sea:
Then Moshe and the people of Israel sang this song to God, saying, ‘I will sing to God, for he has triumphed gloriously; the horse and its rider has he thrown into the sea. (15:1) …And Miriam answered them, 'Sing to God, for he has triumphed gloriously; the horse and his rider has he thrown into the sea. (15:21)
The main thrust of the song of praise focuses on "the horse and the rider.” The Netziv explains that this hierarchic military formation - the rider of the subjugated horse obeys the officer, who in turn takes orders from the general, who obeys the commander in chief – was the personification of Egyptian society, which was nothing more than a series of horses and riders, with the Jewish slaves at the bottom of the proverbial totem pole. The lowliest beast of burden supported the entire structure, which explains why the Egyptians were loath to release their slaves: Society would crumble without them. This also explains why the death of the firstborn was so essential to the Exodus, and why the splitting of the sea evoked such a powerful response. The horse-and-rider philosophy sank into the depths of the sea right before their eyes, and the Jews were freed not only of their oppressors but of the philosophy that had facilitated and even necessitated their oppression. The death of the firstborn was the beginning of the end of Egypt, the true catalyst for redemption: The highest echelons of society, the leading "riders," were toppled.Not only was Egypt defeated, but the entire corrupt regime was overturned, the pyramid upended.
This turning of the tables is expressed in another Midrash that challenges the generally accepted understanding of the final plague.
מדרש תהלים - מזמור קלו
למכה מצרים בבכוריהם. בשעה ששלח הקב"ה מכת בכורות, א"ל, כחצות הלילה ומת כל בכור. נכנסו כל הבכורות אצל אבותיהם, ואמרו להם, כל מה שאמר משה הביא עלינו, אין אתם מבקשים שנחיה בואו והוציאו את העברים האלו מבינינו, ואם לאו אנו מתים. השיבו להם ואמרו, אפילו כל המצרים מתים אינן יוצאים מכאן. מה עשו, נכנסו כל הבכורות אצל פרעה והיו מצווחין לפרעה ואומרים, בבקשה ממך הוציא את העם הזה שבשבילם רעה תבוא עלינו ועליך. אמר לעבדיו, צאו וקפחו שוקיהם של אלו. מה עשו הבכורות, מיד יצאו ונטלו כל אחד חרבו והרג את אביו, שנאמר, למכה מצרים בבכוריהם. למכה בכורי מצרים אין כתיב כאן, אלא למכה מצרים בבכוריהם. ששים רבוא הרגו הבכורות באבותיהם.
"To him who struck Egypt with their firstborn"(Psalms 136:10). When God sent the plague of the firstborn…All the firstborn went to speak to their fathers and said "Everything which Moshe has said has come true. Don't you want us to live? Let us get the Hebrews out of our homes - otherwise, we are dead." The fathers answered, "Even if all of Egypt dies, they are not leaving." All the firstborn gathered in front of Pharaoh and screamed, "Please remove this nation, because of them evil will befall us and you." Pharaoh said to his servants, "Remove them and break their knees." What did they do? Each (firstborn son) took a sword and killed his father, as it is written: ‘To him who struck Egypt with their firstborn.’ The text does not read, “To Him who struck the firstborn of Egypt;” rather, “To Him who struck Egypt with their firstborn.” Six hundred thousand fathers were killed by their firstborn. (Midrash Tehilim 136:6)
This midrash conveys the unraveling of Egyptian society: Children rebelled against their fathers,horses rebelled against their riders, and the underpinnings of Egyptian society were swept away.
By now, it is clear that the death of the firstborn was not just one more plague, one more display of Divine might. This plague struck at the very epicenter of Egyptian civilization and paved the way for liberation. The stage was set much earlier, though, for the showdown between Egyptian philosophy and the Jewish concept of birthright. In a very real sense, the entire book of Bereishit is a polemic against the concept of primogeniture and the privilege of the older son.Birth does not guarantee position. Moreover, the term “firstborn” does not express an immutable biological or chronological fact. The status of firstborn may be forfeited or acquired, earned or lost. While Judaism sets aside a special role for the firstborn, as Rav Soloveitchik explained, this is more a reward for the eldest’s additional responsibilities, not a privilege or right.
When God sends Moshe to demand the release of the Jews, He refers to Israel as His firstborn son; it may be argued that this is inaccurate. Esav/Edom – and not Yaakov/Yisrael, was the eldest.
What is the meaning of ‘Israel is my son, my firstborn?’ It refers to Yaakov their forefather who purchased the birthright in order that he might serve God. [Hence] ‘And you shall say to him: Let My son go, that he may serve Me.’(Midrash Shmot Rabbah 5:7)
God confirms Yaakov’s status as firstborn, which is far from self-evident. But it is not the order of birth or the bargain Yaakov struck with Esav that entitles him to this status. It is Yaakov's commitment to the service of God that transforms him and makes him worthy of the status of "firstborn." On the other hand, "real" firstborns have lost their status:
Instead of every firstborn that opens the womb among the children of Israel (3:12). Originally the Temple service devolved upon the firstborn, but when they committed the Sin of the Golden Calf the Levites, inasmuch as they had not erred in the matter of the Calf, were privileged to enter in their stead. (Midrash Rabbah - Bamidbar 4:8)
Divine service utilizes the principle of "first come first served"the firstborn therefore had the right and responsibility to serve God, the sin of the Golden Calf forfeited for them this lofty responsibility. From the dawn of time there have been those willing to serve God, and others who have ignored or rejected such opportunities:
Go back to the beginning of the creation of the world. Adam was the world's firstborn. When he offered his sacrifice, as it says: And it pleased the Lord better than a bullock that hath horns and hoofs (Tehilim 69:32) - he donned high priestly garments; as it says: And the Lord God made for Adam and for his wife garments of skins, and clothed them (Gen. III, 21). They were robes of honor which subsequent firstborn used. When Adam died he transmitted them to Seth. Seth transmitted them to Methusaleh. When Methusaleh died he transmitted them to Noah. Noah arose and offered a sacrifice; as it says: And he took of every clean beast... and offered burnt-offerings on the altar (Gen. VIII, 20). Noah died and transmitted them to Shem. But was Shem a firstborn? Japheth, surely, was the firstborn; as it says: Shem... the brother of Japheth the elder1 (Gen. X, 21)! Why then did he hand them on to Shem? Because Noah foresaw that the line of the patriarchs would issue from him. There is proof that Shem offered sacrifices; since it says: And Melchizedek, king of Salem brought forth bread and wine; and he was priest of God the Most High (Gen. XIV, 18). Now was it to him that the priesthood was given? The priesthood, surely, was not given to any man until Aaron arose. What then is the meaning of the statement here, ‘and he was priest’? Because he offered sacrifices like priests. Shem died and handed it on to Avraham. But was Avraham a firstborn? The fact is that because he was a righteous man the birthright was transferred to him, and he offered sacrifices; as it says: And offered him up for a burnt-offering in the stead of his son (Gen. XXII, 13). Avraham died and handed it on to Isaac. Isaac arose and handed it on to Yaakov. But was Yaakov a firstborn? No; but you find that Yaakov prudently took it [the birthright] from Esav. He said to him: Sell me first thy birthright (Gen. XXV, 31). Do you suppose perhaps that it was for no good reason that Yaakov asked Esav to sell him the birthright? No! Yaakov wished to offer sacrifices and could not, because he was not the firstborn. (Midrash Rabbah - Bamibar 4:8)
The lineage of the Jewish people is the antithesis of Pharaoh, instead of firstborn after firstborn after firstborn, the spiritual legacy which we carry is of those who chose to serve God regardless of station, and at times despite modest ancestry.This is the significance of God's resounding declaration that we are His firstborn.
"’But I will harden his heart’ (4:21)- to exact retribution from them. ‘And you shall say to Pharaoh, "Thus said the Eternal God: ‘Israel is my son, my firstborn; … I will slay your son, your firstborn.’ (ib. 22-3). God revealed to him that Pharaoh would not let Israel go free before the plague of the first-born; hence there was no need to tell him of this plague later.”
"God brought the ten plagues upon them in accordance with the regular plan of campaign; and of these, the frogs were the most grievous, as it says: 'And frogs, which destroyed them' (Ps. 68:45). They destroyed their bodies and emasculated them. Midrash Rabbah Shmot 15:27
The Ibn Ezra says that the death of the Egyptian first born was the main objective of the Exodus. See Ibn Ezra on Tehilim 135:8. A somewhat less sweeping statement may be found in Ibn Ezra’s comments on Shmot 34:19.
אבן עזרא תהלים פרק קלה פסוק ח
והזכיר תחלה מכת בכורות - בעבור שני דברי' האחד כי עיקר יציאתנו ממצרי' היה בעבור מכת בכורות וכן כתוב הנה אנכי הורג את בנך בכורך והשני בעבור שנמלטו בכורי ישראל והנה היה נס בתוך נס:
אבן עזרא הפירוש הקצר שמות פרק לד פסוק יט
כל פטר רחם לי - זכר ליציאת מצרים, כי בעבור מכת בכורות יצאנו ממצרים.
…וכן היה במצרים שהוסיפו להרע כי השליכו בניהם ליאור, וימררו את חייהם וחשבו למחות את שמם, וזה טעם דן אנכי - שאביא אותם במשפט, אם עשו כנגזר עליהם או הוסיפו להרע להם. וזהו מה שאמר יתרו כי בדבר אשר זדו עליהם (שמות יח יא), כי הזדון הוא שהביא עליהם העונש הגדול שאבדם מן העולם. וכן כי ידעת כי הזידו עליהם (נחמיה ט י):
This midrash goes on to report a tradition that Avraham was told about the plague of the firstborn, and subsequently passed this information to his descendants.
The breakdown of Egyptian morality that precipitated its collapse is an important point of reference in the Torah, as reflected in the exhortation (Vayikra 18:3): ‘Do not do what was done in the land of Egypt, where you dwelt.’
סוס ורכבו רמה בים. זהו תמצית השירה כמובן משירת הנשים, שלא אמרו אלא זה המקרא. והענין דבמשמעות סוס ורוכבו נכלל הכל, דכמו הסוס המוכן למלחמה נשמע לרוכבו, כך האיש חיל הוא כסוס לאדוניו להתהלך באש ובמים, והגדול ממנו הוא כסוס לשר האלף, ושר האלף לראש שרי צבאות עד פרעה עצמו. וגם נכלל בזה השר העליון הרוכב על המערכה העליונה של פרעה, ולאותו השר העליון הרי כל המערכה נחשבת כסוס, וכל אלה רמה בים, וזהו כי גאה גאה. גאה על כל הגאים. ובזה יבואר מקרא בשה"ש [א' ט'] לססתי ברכבי פרעה דמיתיך רעיתי, כמו הסוס ברכבי פרעה נכלל בזה הנהגת המלוכה בכלל, כך ישראל המה סוס של הקדוש ברוך הוא כביכול שע"פ מעשיהם והשגחה שעליהם מנהיג העולם, וכדכתיב בפ' ברכה [דברים ל"ג כ"ו] רוכב שמים בעזרך, וכאשר יבואר שם ברצות האל הגומר עלי:
The Zohar describes the breakdown in a slightly different manner:
Mark the wondrous punishment that overtook the enemies of Israel. On the night of the Exodus there were three slayings in Egypt. First, the firstborn killed whomsoever they could lay hands on; then, the Holy One executed His judgement at midnight; and, lastly, Pharaoh, on seeing the havoc wrought upon his own household, himself arose and with bitterness and fury smote those princes and nobles who had advised him to persecute Israel. He rose up at midnight; yea, even at the hour and moment when the Holy One Himself began His judgement (Ex. XII, 30), did Pharaoh likewise rise up in wrath, and kill his officers and nobles, just as a dog, if hit with a stone, goes and bites another dog. Having done this, Pharaoh roamed through the market places crying, “Rise up and get you forth from among my people” (lbid. v, 3I); and in fear he added, “and bless me also” (v. 32), as if to say, “let me live”. Then, so eager was he to be rid of them that he himself accompanied them, as it says, “he sent the people away” (Beshallach, lit. escorted). Zohar, Shmot, Section 2, Page 45b
 One gets a sense of the polemical quality of the plagues from numerous sources. For example: Midrash Rabbah - Exodus XV:15 "This month shall be unto you (XII, 2). Another explanation: It is written: He sent Moshe His servant, and Aaron whom He had chosen (Ps. CV, 26). As soon as G-d, as it were, entered, He smote their firstborn and their gods, for it says: And I plagued Egypt (Josh. XXIV, 5). Also among their gods did the Lord perform judgments."
Zohar, Shmot, Section 2, Page 29a "Esoterically speaking, the ten plagues were wrought by the mighty hand of the Almighty, by the hand that overpowered the grades of the Egyptian divinities, and confused their minds so that they remained helpless. Observe that all their grades, as soon as they emerged into the open to accomplish something that could be seen by all, became powerless to do anything. This was due to the mighty hand which pressed on them."
The Zohar: (Zohar Bereishit 36b) points to a spiritual deficiency in the very first – firstborn.
When they begat children, the first-born was the son of the (serpent's) slime. For two beings had intercourse with Eve, and she conceived from both and bore two children. Each followed one of the male parents, and their spirits parted, one to this side and one to the other, and similarly their characters. On the side of Cain are all the haunts of the evil species, from which come evil spirits and demons and necromancers. From the side of Abel comes a more merciful class, yet not wholly beneficial-good wine mixed with bad. The right kind was not produced until Seth came, who is the first ancestor of all the generations of the righteous, and from whom the world was propagated
In a lecture delivered on February 8th, 1975 in Boston,
 This is reflected by the protocol of Temple service as can be seen in the Mishna of Tamid or Yoma.
The Midrash (Shmot Rabbah 19:7) states that the Messiah will be called a firstborn
"Sanctify unto me all the firstborn "(13:1). R. Natan said: The Holy One, blessed be He, told Moshe: 'Just as I have made Ya'akov a firstborn, for it says: Israel is My son, My firstborn (ib. 4:22), so will I make the King Messiah a firstborn, as it says: I also will appoint him firstborn (Ps. 89:28). (Midrash Rabbah - Exodus 19:7)
 Rabbi Soloveitchik (February 8th, 1975) pointed out that by calling us His firstborn, God is clearly saying that He has other children as well. The rage directed against Egypt was partially due to the fact that as long as the Jews were subjugated, they could not receive the Torah and inspire the other "children" by being a "Light unto the nations".