In the end, his flaws outweighed his intelligence and ability and helped to render hollow his great victory at Charleston

From The Road to Guilford Courthouse by John Buchanan. Page 71.

We indicated previously that Sir Henry, not a great general but quite competent and the most able of the four British commanders in chief during the American Revolution, had a seriously flawed personality. In the end, his flaws outweighed his intelligence and ability and helped to render hollow his great victory at Charleston. “He was driven by an urge to quarrel,” his biographer William Willcox wrote, and this judgment cannot be faulted. The British generals who served in America were as a lot quarrelsome, but Clinton was in a class by himself. He could not get along with his peers or his superiors. He had one of the most irritating traits in the collection of human failings: a total lack of tact. “I have accustomed myself, wherever I go, to hear all [and] see all I can, and form my own sometimes mistaken opinions in consequence.” All very well had he kept those opinions, mistaken or otherwise, to himself, or had he been able, in the manner of a skilled courtier, to pass them on to his superiors without angering them. A “shy bitch,” as he called himself, he never exhibited that part of his personality when laying out to his superiors their failings as commanders. Yet as commander in chief he could not bring himself to be equally blunt in face-to-face confrontations with subordinates who challenged his authority. As subordinate himself he failed to take into account the feelings and pride of superiors; in command he failed to exert his authority over subordinates who challenged his authority. As subordinate himself he failed to take into account the feelings and pride of superiors; in command he failed to exert his authority over subordinates. He planned so very well, but with the exception of the Charleston campaign lacked the strength of character to carry out those plans. He was indeed a most neurotic man, and the reasons for his condition elude us.