Their empire collapsed when their camps and villages were repeatedly decimated by epidemics of smallpox and cholera in the late 1840s, and in bloody conflict with settlers, the Texas Rangers, and the U.S. Army. The population plunged from 20,000 to just a few thousand by the 1870s. The Comanche were no longer able to deal with the U.S. Army, which took over control of the region after the Mexican–American War ended in 1848. The long-term imprint of the Comanche on the Indian and Hispanic culture has been demonstrated by scholars such as Daniel J. Gelo and Curtis Marez.