Yes, I have too. Here is a link to the Merrill's Horse regimental history website which reports that "SERVICE.--Moved to Northern Missouri and duty at Columbia, Glasgow, Sturgeon, Paris, Huntsville, Palmyra and Warrenton, operating against guerrillas January, 1862, to June, 1863."

http://www.usgennet.org/usa/mo/county/stlouis/merrill.htm

I think with the dialogue of all who have contributed here, we may draw a conclusion that "Warrenton" also included Hummel's farmsite near Truesdale, which was noted to be the site of Camp Annie on a Union soldier's discharge ticket; and that Camp Annie may have been named after General Lewis Merrill's wife Annie Rhoda Houston.

If a Civil War historical site marker has not been authorized and placed noting that Union forces utilized the Hummel farm near Truesdale (aka Camp Annie) during the, then perhaps the powers that be from Missouri might want to consider it.

Thanks for everyone's input.