[1] In 1848, he matriculated at the Virginia Military Institute, graduating four years later, fifth in his class,[1] with fellow Page countians Simeon Beauford Gibbons and Hiram Jackson Strickler, as well as later Confederate notables, Thomas T. Munford, James A. Walker, Joseph C. Mayo, and George Smith Patton Sr. One of the signatures on his diploma was that of Thomas Jonathan Jackson.
Following graduation, Yager worked briefly as a banker in Virginia, and soon after traveled to Kansas with fellow Page countian and VMI classmate Hiram Jackson Strickler, taking with him several slaves, including a valet.
Relocating to Texas, Yager settled in Seguin, Guadalupe County, where he met Mary Elizabeth Rhodes, whom he married in 1863.
[1] He spent the autumn and winter of 1861 with this unit in Central Texas and engaged in sporadic negotiations and skirmishes with local Indian groups.
Following Buchel's mortal in action at the Battle of Pleasant Hill, Louisiana, on April 9, 1864, Yager was elevated to colonel and command of the regiment.