Ross attempted to restore political unity after the arrival in Indian Territory. Unknown people assassinated the leaders of the Treaty Party except for Stand Watie, who escaped and became Ross's most implacable foe. The issue of slavery soon refueled the old divisions. The Treaty Party morphed into the "Southern Party," but the National Party largely became the "Union Party." Ross initially counseled neutrality since he believed that joining in the "white man's war" would be disastrous for the future unity of their tribe. After the Union Forces abandoned their forts in Indian Territory, Ross reversed himself and signed a treaty with the Confederacy. He later fled to Union-held Kansas, and Stand Watie became the "de facto" chief. The Confederates lost the war, Watie became the last Confederate general to surrender, and Ross returned to his post as principal chief.