Brock likely assured Tecumseh that the British would support Indian land claims. He wrote his superiors that restoration of land "fraudulently usurped" from the Indians should be considered in any peace treaty. News of Detroit's capture revived British discussion of creating of an Indian barrier state to ensure the security of Upper Canada. After his short stay in the area, Brock returned to the Niagara frontier, where he was killed in action several weeks later. Meanwhile, the British had negotiated a temporary armistice and called off further offensives. Tecumseh was frustrated by the unexpected British-American armistice, which came at a time when his confederacy was attacking other American forts and were in need of British support. In September 1812, he and Roundhead led 600 warriors to assist in an attack on Fort Wayne, but the siege failed before they arrived. Another siege against Fort Harrison also failed. Tecumseh stayed in the Prophetstown region for the remainder of 1812, coordinating Indian war efforts.