For what purpose did the pharaohs organize military campaigns to other countries?

In the civilization of Ancient Egypt, the pharaohs organized military campaigns against nearby states and tribes in order to enrich themselves. So the society was arranged that the ruling pharaoh should be the richest person in the state. Pharaoh owned not only wealth, but also slaves who did the dirty work. Tombs and palaces were built for the ruler of Egypt. Often this happened at the expense of the labor force and wealth of the captured country or tribe.