In 1854 Sinclair led a second large group of Red River settlers on a secret journey to Fort Nez Percés. He had been promised 200 head of cattle by the HBC for doing so. Upon reaching the Rockies he followed the Kananaskis River south and made a difficult crossing following the Elk River into the Columbia-Kootenay's. He died in an Indian attack at the Cascades settlement on the Columbia, March 26, 1856.