Complex sentence: No white man could be found to undertake a dangerous mission to find Red Cloud and bring him to Fort Laramie for negotiations, so several of the loafers undertook the task and on March 12,1866, Red Cloud and his Oglala rode into Fort Laramie.
Split into simpler sentences: No white man could be found to undertake a dangerous mission to find Red Cloud and bring him to Fort Laramie for negotiations, so several of the "loafers" took the task. On March 12,1866, Red Cloud and his Oglala rode into Fort Laramie.