sentences:  This began the process of annexing Hawaii to the U.S.
  
  On December 2, 1845, U.S. President James Polk announced that the principle of the Monroe Doctrine should be strictly enforced, reinterpreting it to argue that no European nation should interfere with the American western expansion ("Manifest Destiny").In 1862, French forces under Napoleon III invaded and conquered Mexico, giving control to the puppet monarch Emperor Maximilian.Washington denounced this as a violation of the doctrine but was unable to intervene because of the American Civil War.