Words of Mormon 1:18

wherefore, with the help of these, king Benjamin, by laboring with all the might of his body and the faculty of his whole soul, and also the prophets, did once more establish peace in the land.

With the help of these holy men, King Benjamin worked with all his strength and all his heart. The prophets helped too. Together they brought peace to the land again.

So with their help, King Benjamin—working with all his strength, body and soul, alongside the prophets—brought peace to the land once more.