|The gunboat Philadelphia from Arnold's fleet|
A year before Benedict Arnold saved his country by winning the Battle of Saratoga he saved his country by losing the Battle of Valcour Island.
Valcour Island was an unusual "b\naval" battle as it was fought on Lake Champlain, which is a large, but not enormous lake. The strategic significance of Lake Champlain is that, while not especially large, it is very long, making it an excellent "highway" for a supply line for an Eighteenth Century army in an otherwise nearly road-less wilderness.
In 1776 the British intended to advance from Canada using the long and narrow Lake Champlain as their main supply route.
The Americans built a fleet and Arnold, who had experience at sea from his pre-war business career, took command. The British were forced to also build a fleet to protect their supply line. On Oct. 11, 1776 those two fleets, about 15 vessels for the Americans and two dozen for the British met in battle at Valcour Island, about halfway down the lake. While Arnold's fleet was destroyed, the mere fact it existed and the British had been forced to deal with it delayed the campaign that year so late into the season that the British invasion had to be suspended.
Almost exactly a year later a second British effort down that path led to the decisive Saratoga campaign.