A major difference between a slave people and a free people is that a free people has not only the ability but also the duty to defend itself. This is a theme that runs throughout the Torah and indeed the entire Bible.

In the story of the Exodus, the struggle to free the Israelites is conducted entirely by G-D through miracles that are presented by His spokesmen, Moses and Aaron. The people of Israel do not rise up and do not fight for their freedom. This is true even at the Sea of Reeds, the climax of redemption, when they are specifically told: " G-d will fight for you; you keep still!" (Exodus 14:14). This is emphasized when the Egyptians say, "The L-rd is fighting for them against Egypt" (Ex. 14:25) and verse 14:30, which sums up the story with the words "Thus the L-rd delivered Israel that day from the Egyptians."

Yet very soon thereafter, their first test as a free people is to defend themselves in the battle against Amalek, not to depend only upon a miracle from the G-d. For the first time, Moses commands Joshua, "Pick some men for us and do battle with Amalek  " (Ex.17:9). It is a battle in which they triumph, " And Joshua overwhelmed the people of Amalek with the sword" (Ex. 17:13).

Unfortunately, this triumph does not continue throughout the wilderness story. Their fear overcomes them all too often, and they express a desire to return to Egypt rather that face the difficulties of defending themselves. This reaches its moment of disaster when, listening to the report of the spies, they refuse to continue the journey and undertake the battle for the land, preferring to die in the wilderness. "Why is the G-d taking us to the land to fall by the sword?" (Numbers 14:3), they ask, and they determine to head back for Egypt. As a result, they must remain in the wilderness for 40 years so that the entire generation will die out and never reach the land of promise (Num. 14:26-35). The Rambam in Moreh Nevuchim states that a slave generation is not capable of fulfilling the task of fighting and conquering the land of Israel.

This theme repeats itself again at the conclusion of their journey in the story of the tribes that ask Moses's permission to remain behind on the other side of the Jordan, an area not considered fully part of the land of Israel. Moses rebukes them with the caustic rhetorical question, " Shall your brothers go to war while you remain here?" (Num. 32:6). The sin of these tribes in the eyes of Moses, is not only that they want to remain in Transjordan but that they, like their fathers, are not willing to fight for their freedom and will cause all Israel to turn and flee (Num. 32:14-15).

Only when they explain that indeed they  are willing to fight – "We will hasten as shock-troops in the forefront of the Israelites until we have established them in their home …" (Numbers 32:17) – does Moshe grant their request.

We find this same idea in the stories told of the period of the Judges. In the Song of Deborah, for example, the tribes that did not join in battle are castigated for their timidity (Judges 5:15-17). Those who "came not to the aid of the L-rd, to the aid of the L-rd among the warriors" are even bitterly cursed (5:23).

Deuteronomy stresses the need for all the males of appropriate age to fight in Israel's wars and lists those who are exempt: one who has built a new home and not dedicated it, one who has planted a vineyard and not harvested it, one who has betrothed a woman but not married her, one who is afraid and might cause others to be fightened (Deuteronomy 20:5-8). Those are the only exemptions.

The Mishna, determined that even these exemptions applied only to certain types of warfare – those that were not mandatory, but that in required wars such as Milchemet Mitzvah – a war of  self defense, "all must serve, even the groom from his room and the bride from her canopy" (Sota 8:6).

Just as Israel had to change from a nation of slaves and become a free people and in so doing take upon themselves the responsibility for their own defense and the lives of the entire people, so too the emergence of a free Jewish state mandated such a change. While asking for G-d's help, we can no longer be passive in our own defense. That is what it means to be a free people. And the Lubavitcher Rebbe stated that one who serves in the IDF is engaged in Milchamet Mitzvah 24/7.