The Tongue River in northern Wyoming must have been as beautiful as it is now when George Bent saw it in 1865, with big, lazy curves under cottonwoods, the grass thickening on its banks and the trees sending out their first green shoots in early May. Nowadays, irrigated hay fields and the tiny towns of Dayton and Ranchester lie along the river. In May of 1865, however, one stretch of it was packed with human beings. That month, there was as large a town on the Tongue as that river has ever seen.