1 Kings 16:16

And the people that were encamped heard say, Zimri hath
conspired, and hath also slain the king
Tidings came to the army of what he had done, which was displeasing to them:

wherefore all Israel made Omri, the captain of the host, king over
Israel that day in the camp;
that is, all Israel that were in the army proclaimed Omri, their general, king; just as the Roman army declared Vespasian, their general, emperor of Rome, and as several of the emperors were chosen.