Alma 47:21

And the king came out to meet him, with his guards: for he supposed that Amalickiah had fulfilled his commands, and that Amalickiah had gathered together so great an army for to go against the Nephites to battle.

The king came out to meet him with his guards. The king thought Amalickiah had obeyed his commands. He thought Amalickiah had gathered a big army to fight against the Nephites.

The king came out with his guards to meet him, assuming Amalickiah had fulfilled his orders and assembled this massive army to attack the Nephites.