Benedict Arnold was an interesting, but tragic figure. He was a very efficient general and he fought hard and extremely well for the revolutionaries in the early going, but he seems to have been overly ambitious and egotistical. Accordingly, he began to feel that he had not received enough reward for his efforts (in the form of promotion, I suppose, or other rewards). He became disgruntled with the revolutionary command, feeling that he was not being accorded the degree of respect and attention he felt he was deserving of.

In this mood, he seems to have come to the conclusion that he could do better with the British if he changed sides. Perhaps he also felt that the British were more likely to win the war....in fact, having a reputedly very high opinion of himself, he probably figured that the British would win for sure if he lent them his considerable talents in the field.

As it turned out, his plans went a bit awry, and he had to depart the American side in unseemly haste to save himself from being caught as a turncoat. His ambitious plans came to nothing. The British did not make much use of his services, as far as I know, and he lived out his life miserably in later years as an exile in England, a man essentially without a country.