The two scientists' attention turned to the Dakota Territory in the mid-1870s, where the discovery of gold in the Black Hills increased Native American tensions with the United States. Marsh, desiring the fossils found in that region, became embroiled in Army-Indian politics. In order to gain the support of Chief Red Cloud of the Sioux to prospect, Marsh promised Red Cloud payment for fossils collected and that he would return to Washington, D.C. and lobby on their behalf about their improper treatment. In the end, Marsh slipped out of camp and according to his own (possibly romanticized) accounts, amassed cartloads of fossils and retreated just before a hostile Miniconjou party arrived. Marsh, for his part, did lobby the Interior Department and President Ulysses S. Grant on behalf of Red Cloud, but his motives might have been to make a name for himself against the unpopular Grant administration. By 1875, both Cope and Marsh paused in their collecting, feeling financial strain and needing to catalogue their backlogged finds, but new discoveries would return them to the West before decade's end.