The Battle of Lake Whatcom was a month-long campaign during the Alaskan War to dislodge Alaskan defensive positions in the Chuckanut Mountains south of Bellingham in what is the present-day U.S. state of Washington. Fought in August of 1885, the fighting marked the beginning of the long and arduous rollback of Alaskan troops from American territory and was the first offensive victory for the United States in the Oregon Theater.
Due to the narrow passes running through the low mountains and the easily defensible positions that this allowed the Alaskans, a disproportionate number of American soldiers were killed. However, the Alaskans were outnumbered in the mountains and, reluctant to directly engage the Americans in such close quarters, Alaskan leader Boris Anasenko elected to withdraw after the westernmost defenses, on the coast of the Puget Sound, were overrun on August 24th, and after American soldiers dislodged the artillery battery at Hooper's Ranch along Lake Whatcom on August 26th. In all, the Americans suffered 11,232 casualties (including 2,344 dead) against 1,441 Alaskan casualties (including 349 dead), making it what US Commander of the Army of Oregon George Jameson described as a "pyrrhic victory in every sense of the word."
However, the Americans would defeat Alaskan soldiers in the Second Battle of Bellingham only a few days later and score themselves a substantially improved base of operations north of the Chuckanut Mountains.