Arnold was born in Connecticut and was a merchant operating ships on the Atlantic Ocean when the war began in 1775. He joined the growing army outside Boston and distinguished himself through acts of intelligence and bravery. His actions included the Capture of Fort Ticonderoga in 1775, defensive and delaying tactics at the Battle of Valcour Island on Lake Champlain in 1776 which allowed American forces time to prepare New York's defenses, the Battle of Ridgefield, Connecticut (after which he was promoted to major general), operations in relief of the Siege of Fort Stanwix, and key actions during the pivotal Battles of Saratoga in 1777, in which he suffered leg injuries that halted his combat career for several years.