Alma 53:17

and they entered into a covenant, to fight for the liberty of the Nephites; yea, to protect the land unto the laying down of their lives; yea, even they covenanted that they never would give up their liberty, but they would fight in all cases to protect the Nephites and themselves from bondage.

They made a promise to fight for the freedom of the Nephites. They promised to protect the land even if it meant dying. They promised they would never give up their freedom. They would always fight to protect the Nephites and themselves from being slaves.

They made a covenant to fight for the freedom of the Nephites, to protect the land even if it cost them their lives. They swore they would never surrender their liberty but would fight to the end to keep themselves and the Nephites from bondage.