Decimating Egypt: Why Not Plague 11?
In the beginning of Parshas Beshalach, God wipes out the Egyptians in the Yam Suf. Why did God wait until this point to wipe out the Egyptians? He could have wiped out the entire nation during Makas Bechoros, instead of wiping out only the firstborns. Or He could have made an 11th plague that wiped out all of the Egyptians. If you want to say that the Egyptians didn’t deserve death until this point, what changed that made them deserving of death after chasing the Jews at Yam Suf? Alternatively you could say that the Egyptians deserved to be wiped out beforehand, but God waited until this point to execute justice. If that is the case, why was it necessary for them to be wiped out at this later time?
If we examine how the Jews related to the Egyptians, it helps us understand why the timing of the events at Yam Suf was important in the development of the nation. After the Jews left Egypt, the Egyptians soon regretted granting their freedom and chased after them. When the Jews saw the pursuing Egyptian army in the distance, they became frightened and said to Moshe, “Were there not enough graves in Egypt that you brought us to die in the wilderness? What have you done to us, taking us out of Egypt?” (Shemos 14:11) . Although the Jews had left Egypt physically, they were still very tied to Egypt and felt drawn to return to Egypt.
We see this attachment to Egypt earlier in the Parsha: “When God took the Jews out, He didn't take them by way of the Philistines which was closer, lest they see war and return to Egypt” (Shemos 13:17). Why would the Jews want to return to Egypt?! There are many other directions to travel. Why would they want to go back to the place where they had been enslaved?
This shows us that despite having left Egypt, the Jews continued to feel an attachment to Egypt and an acceptance of Egyptian authority. They even preferred this authority over freedom. Egypt was where they had been living for 210 years, and they felt a certain security there. However, it was important for the Jews to fully dissociate from Egyptian authority before they could accept God's authority at Sinai, which is the reason they were taken out.
This answers our original question: The Egyptians deserved to be punished due to their crimes of persecuting the Jews during 210 years of bondage. The ideal time to exact this punishment was after the Jews had openly expressed their continued subservience to Egypt. Witnessing the events at Yam Suf helped break the attachment of the Jews to Egypt as an authority, and start on the path of becoming a nation who recognizes that their only authority is God.