 The American strongholds of Fort Crown Point and Fort Ticonderoga near the lake 's southern end protected access to uppermost navigable reaches of the Hudson River . Elimination of these defenses required the transportation of troops and supplies from the British @-@ controlled St. Lawrence Valley 90 miles ( 150 km ) to the north . Roads were either impassable or nonexistent , making water transport on the lake the only viable option . The only ships on the lake following the American retreat from Quebec were a small fleet of lightly armed ships that Benedict Arnold had assembled following the capture of Fort Ticonderoga in May 1775 . This fleet , even if it had been in British hands , was too small to transport the large British Army to Fort Ticonderoga . 
