Frank Knox was a Republican who was asked by a Democratic president to serve his country in a time of danger. Knox was the publisher of the Chicago Daily News starting in 1930. Under his leadership, the newspaper had a conservative and pro-Republican editorial policy.
In 1936, Republican Gov. Alf Landon of Kansas asked Frank Knox to be his running mate as the Vice Presidential nominee against the Democratic ticket of Franklin D. Roosevelt of New York and John Nance Garner of Texas. FDR won in a landslide. Landon and Knox carried only two states, Maine and Vermont.
But in 1940, FDR realized he needed to reach out to Republicans to build bipartisan support for his pro-British foreign policy and the lend-lease program whereby America would let Great Britain borrow surplus American ships to fight Nazi Germany. This was not a neutral policy and FDR knew it and so did the Germans. In a typically astute political move, FDR asked Knox, a nationally prominent Republican, to serve as Secretary of the Navy in his administration and the pro-British Knox agreed. He was on duty on the Sunday of the Pearl Habor attack on Dec. 7, 1941. Within days he was on his way to Hawaii on a fact-finding mission.