Answer:
Telegraph
Explanation:
The England's Orders in Council which was issued in November and December 1807, which imposed a blockade on Napoleonic Europe by the British and, in response, the decree by which the French might seize any neutral ship that complied with the British regulations.
If the Americans were aware of the repeal of England's Orders in Council, they may not have gone to war. The invention of the Telegraph would have prevented that as the relay of information would be faster