a) Conquest is the act of military subjugation of an enemy by force of arms.[1][2] Military history provides many examples of conquest: the Roman conquest of Gaul, the Mauryan conquest of Afghanistan and of vast areas of the Indian subcontinent, the Spanish conquest of the Aztec Empire and various Muslim conquests, all of which were successful in bringing foreign states under the conquerors' control. These conquests provided great wealth, power and prestige for the conquerors, a key motivation in the expenditure of resources required to conquer in the first place. Conquest was a key component of colonialism, as various European powers sought to expand their influence by conquering various territories of other continents and thereby gaining access to their resources and population. Military conquest is no longer prevalent in the world, as global unity increased with the formation of the United Nations, so too did global disapproval of military conquest and expansionism.
b) Islam spread through military conquest, trade, pilgrimage, and missionaries. Arab Muslim forces conquered vast territories and built imperial structures over time.
