in late 1881, the 9th cavalry was transferred to the southern plains. day was promoted to first lieutenant in 1884 and assigned to i troop, which was stationed at fort reno near present-day oklahoma city. the troop was responsible for removing white settlers known as "boomers" from the unassigned lands located in the middle of what is now the state of oklahoma. during this time, day became something of a celebrity through his skill as a marksman by winning the annual rifle marksmanship contest for the u.s. army's division of the missouri. he also captained the team which represented the division of the missouri in competition against opposing teams from the divisions of the atlantic, pacific, and artillery. the team won the long-distance target shooting competition and day himself was acknowledged to be "'the best skirmisher'" when involved in a competition that involved "shooting at targets under conditions 'that were an approximation to actual service'".