You'll use "brutal" far more often than you'd use "brute". It seems that "brute" is limited to a few collocations (brute force, brute strength), and even then it refers only to non-physical things. In most cases, "brute" is used as a noun. Or a tragic Shakespeare reference.

thank you!

A good question..I'm not very good at english. but i'm going to answer your question as i can.brutal is only an adjective. means 1 violent and cruel 2 direct and clear about something unpleasant.,not thinking of people's feelings. brute~~ is an adjective as well as a noun..the noun"brute" describe a man or animal. when we talk about people and animals we usually don't use brute., because it already have a quality of a man or animal. brute (adjective) means 1 involving physical strength only and not thought or intelligence....2basic,simple and unpleasant. Now here. for a war , most suitable adjective would be, violent and cruel. So it would be A BRUTAL WAR