Original: Before the United States formally entered World War II by declaring war on Japan on December 8 , 1941 , Lindbergh had been an outspoken advocate of keeping the U.S. out of the world conflict , as was his Congressman father , Charles August Lindbergh ( R-MN ) , during World War I , and became a leader of the anti-war America First movement .
Simplified: His father , Charles August Lindbergh , was a lawyer and later a U.S. congressman who was against the United States entering into World War I ; his mother was a teacher .