Thematic Bible: The eastern half assists in the conquest of the country west of the jordan river

And the sons of Reuben, and the sons of Gad, and half the tribe of Manasseh, passed over armed in front of the sons of Israel, as Moses spoke to them; about forty thousand armed men of the army passed over before Jehovah to battle, to the plains of Jericho.

And I commanded you at that time saying, Jehovah your God has given you this land to possess it. You shall pass over armed before your brothers the sons of Israel, all the sons of might. But your wives and your little ones, and your cattle, (I know that you have much cattle), shall stay in your cities which I have given you until Jehovah has given rest to your brothers, as well as to you, and they also possess the land which Jehovah your God has given them beyond Jordan. And then you shall each one return to his possessions which I have given you.

And Joshua spoke to the Reubenites and to the Gadites and to the half tribe of Manasseh, saying: Remember the word which Moses the servant of Jehovah commanded you saying, Jehovah your God has given you rest and has given you this land. Your wives, your little ones, and your cattle shall remain in the land which Moses gave you on this side Jordan. But you shall go armed before your brothers, all the mighty men of valor, and help them read more.
until Jehovah has given your brothers rest, even as you, and they also have possessed the land which Jehovah your God gives them; and you shall return to the land of your possession and enjoy it, which Moses Jehovah's servant gave you on this side Jordan, towards the sunrise.