I agree that Mountain Howitzers was obsolete by the beginning of the war. But, they were used in the Battle of Pine Bluff and several expeditions in south eastern Arkansas (such as Branchville, Mt. Elba, and Noble Lake,) and were still in use by the 5th Kansas US Cavalry as late as Mark's Mill, where at least 1 and maybe 2 were lost in that battle, in late April 1864.

The 2nd US Colored Artillery, Battery "H" was armed with them (The remaining 5th Kansas Guns,) at Pine Bluff until they (2nd US Colored Artillery)were disbanded in 1866.

Was the Confederate Army better equiped than the Union Army in the Trans-mississippi in 1865?