Mormon 4:21

And when they had come the second time, the Nephites were driven and slaughtered with an exceeding great slaughter; their women and their children were again sacrificed unto idols.

When they came the second time, the Nephites were driven back. Many were killed. Their women and children were killed again as gifts to false gods.

On the second assault, the Nephites were driven back and slaughtered in massive numbers. Once again, their women and children were sacrificed to idols.