James Monroe started the Monroe Doctrine and so did James Quincy Adams. It affected America and Europe by this document starting the War of 1812. This document took place in 1812.
The Monroe Doctrine tells us that America will stay neutral. The Disentanglement of European affairs and defense of neutral rights.
This event took place because Europe and Great Britain were always at war. James Monroe wrote the Monroe Doctrine to keep The United States neutral from them both. It affected America by starting the War of 1812. Itr also affected America by keeping them neutral.