When Smith's party left Mexican Alta California and entered the Oregon Country, the Treaty of 1818 allowed joint occupation between Britain and the United States. In the Oregon Country, Smith's party, then numbering 19 and over 250 horses, came into contact with the Umpqua people. The tribes along the coast had monitored the party's progress, passing news of conflicts between the group and indigenes, and the Umpqua were wary. One of them stole an ax, and Smith's party treated some of the Umpqua very harshly in order to force the thief to return it. On July 14, 1828, while Smith, John Turner and Richard Leland were scouting a trail north, his group was attacked in its camp on the Umpqua River.