It was his first leading role on screen, and it was the one which made him immortal. No matter that his career lasted a further fifty years, he'll always be T.E. Lawrence, i.e. Lawrence of Arabia. The only reason he didn't sweap all awards, Oscar included, was Gregory Peck and "To Kill a Mockingbird".
After seven missed nominations, the Academy gave him an honourary Oscar. He almost declined it, saying he wasn't over yet. He wasn't - he got an eighth for "Venus".