The 22nd Amendment was passed as a reaction to what event?
Franklin Roosevelt's 1944 re-election, to a fourth term.
Prior to FDR, nobody had served more than two terms as president. George Washington supposedly said that two terms was enough, and his successors were, for the most part, too gentlemanly to disagree.
Franklin Roosevelt is remembered today as the savior from the Great Depression and World War II. During his terms of office--he served three and was elected to a fourth, but died three months into it--was kind of a polarizing figure. The Republicans hated him with a passion and could not believe that the electorate could keep re-electing him. Theirs, of course, was the party that insisted on the 22nd Amendment preventing anybody from running for a third term, or--in the event of a tragic succession--serving for more than ten years.