The sons of Reuben and Gad had lots of livestock.

They moseyed on over to Gilead, in what is now Jordan, and looked around.  “Hey,” they said.  This is a terrific place to raise animals.”

So they went to Moses and the heads of the tribes and they said “Gilead is a great place for us and our livestock.  We want to stay here and build walled towns for our wives and kids and animals.”

Moses looked at them.  “Look,” he said, “your fathers refused to go fight for the Promised Land and God got really angry at them.  Now here you are, also saying you’re not going in there to fight for it?  Everyone else goes off to war and you just sit here?  Build your walled towns.  Put the women and the kiddies and the goats safely inside them.  But come with the rest of the Children of Israel to fight!”

“OK,” said the Reubenites and the Gadites.  “First we’ll capture Gilead from King Sibon and King Og, and then we’ll go with the community into Canaan.”

Had the Reubenites and the Gadites planned originally to go with the army that was conquering Canaan?  A note in our Tanach, Etz Chaim, says yes. The great scholar Nahmanides thinks Moses misunderstood their request, and that they just hadn’t said clearly that they meant to join the army all along.  (This is according to Rabbi Noach Shapiro in My Jewish Learning.)  But it’s unclear from the text of the Torah whether the Gadites and the Reubenites meant to bail out on the rest of the tribes or not.

In any case, it’s clear that Moses is telling them that they must fulfill their debt to the community before they can settle down to comfortable lives.

During World War II, millions of men were called upon to fight for THEIR country, just like the Reubenites and the Gadites.  They too went and fought for the common good, then returned to live peaceful lives with their wives and children.