How and why did the Battle of Britain affect the US?

The US, among other countries not involved with the European war, were spectators to the Battle of Britain, which took place in the fall of 1940. The only special effect the battle had upon the US; was the fact that Britain and the US speak a common language, and the US had at one time been part of the British Empire (Revolutionary War 1776). In effect, it was like watching our relatives involved in a fight.