Well, there's the Earl of Manchester, in the midst of the English Civil War. Some of the nobles in revolt still thought it would be possible to come to some sort of compromise with Charles I. Manchester was one of the "Peace Party" and pointed out "If we beat the King ninety and nine times yet he is king still, and so will his posterity be after him; but if the King beat us once, we shall be all hanged, and our posterity be made slaves"

But the half-hearted efforts of the Parliamentarians resulted in the conflict dragging on without a sign of an end. The War Party, with Oliver Cromwell, gained power and soon the aristocrats in command were largely replaced by professional officers, and the New Model Army was created. When the Parliamentarians won, they had to confront again what Manchester had said: Charles was King, and if he got free they were all traitors. There was, in the end, no choice but to condemn and execute him.