Joshua 22:12

To war against them. Here is striking proof of Israel’s strict obedience to the law and their veneration for it in the days of Joshua. A single deviation from it (Lev. 17:8, 9; Deut. 12:5-7; 13:12-15) was sufficient to arouse the loyalty of the nine and a half tribes and cause them to go to war even against their brethren. When they heard of the erection of an altar in addition to the one at Shiloh, they were ready to take immediate action lest the worship of Jehovah be defiled. It was not Joshua who summoned the tribes; they came together voluntarily. But probably he, together with Eleazar, counseled them to defer action until an embassage had been sent to the two and a half tribes to verify the rumor.