In ch. 1:14 this expression is translated “armed,” literally “an army in five parts.” The phrase, “prepared for war,” is from a word meaning “stripped” or “equipped for war.”
About forty thousand.
At the last census (Num. 26) the men eligible for military service numbered: Reuben, 43,730 (v. 7); Gad, 40,500 (v. 18); Manasseh, 52,700 (v. 34), or, for the exact half, 26,350. Thus the entire force of the two and a half tribes was about 110,580. They therefore left more than half their number to protect their families and their dwellings. This was not inconsistent with the spirit of their agreement with Moses.