A number of people have said Winston Churchill, but if he had died at 65 years old (at the begining of the Second World War) he would not have been remembered as a particulalry great man or great politician.
As someone else has said, he was great for 5 years, but only average for the rest of his life.
For example there was a TV program on recently about the sinking of the Lusitania in the First World War with the loss of hundreds of civilian lives.
Churchill was head of the Admiltry the time, and some people said the Admiltry was partly to blame for the sinking (did not give enough warning about submarines in the area, and took away naval support from the Lusitania).
The Admiltry then started a campaign (led by Churchill) to take blame off themselves and put it on the captain. They asked people to lie at the inquest and so on.
The pressure on the captain was such that his marriage broke up and he was hounded by the press at the time.
This surely was NOT one of Chuchill's better periods.
More here
http://www.lusitania.net/churchill.html