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

And the sons of Reuben will pass through, and the sons of Gad and half the tribe of Manasseh, brave in battle, before the sons of Israel, as Moses spake to them. About forty thousand drawn out for war, passed over before Jehovah to war, to the desert of Jericho.

And I shall command you in that time, saying, Jehovah your God gave to you this land to possess it; ye shall pass over armed before your brethren, the sons of Israel, all sons of strength. Only your wives and your little ones and your cattle (I knew that much cattle to you) they shall dwell in your cities which I gave to you, Till when Jehovah shall cause your brethren to rest as you, and they also shall possess the land which Jehovah, your God, gave to them on the other side of Jordan: and ye turned back each to his possession which I gave to you.

And to the Reubenites, and to the Gadites, and to half the tribe of Manasseh, Joshua said, saying, Remember the word which Moses the servant of Jehovah commanded you, saying, Jehovah your God causes you to rest, and he gave to you this land. Your wives, your little ones, and your cattle shall dwell in the land which Moses gave to you on the other side Jordan; and ye shall pass over, being brave, before your brethren, all being strong, of the host, and help them; read more.
Till Jehovah shall cause rest to your brethren as you and they also shall inherit the land which Jehovah your God gave to them: and ye turned back to the land of your possession, and ye shall inherit it, which Moses the servant of Jehovah gave to you on the other side of Jordan from the rising of the sun.