We do not have any list of Union Soldiers from Montgomery County, but below is a list pulled from the Arkansas History Commission for records which are available and can be obtained by microfilm, or by ordering the actual record.
Following this listing is a list of Confederate records available from the Arkansas History Commission.
Civil War - Union:
Index to compiled service records of volunteer Union soldiers who served in organizations from Arkansas
Index to U. S. Civil War pension records, Arkansas
Letters received by Sec. of Navy from Squadron commanders, Mississippi Squadron, 1861-1865
History of Arkansas Union Civil War units 1-4th Cavalry & 1-4th Infantry (also Alabama & Arizona units)
Union service records, Arkansas
Index to Arkansas Union service records (Herndon's)
General index to U. S. military pensions, 1861-1934
Index to Black Civil War soldiers, U. S. C. T.
Service records of U. S. Colored Troops, Arkansas
1890 Special census schedules, Civil War Union veterans & their widows: Kentucky-Wyoming
Civil War - Confederate:
Index to compiled service records of Confederate soldiers who served in organizations from Arkansas
Index to Arkansas Confederate service records (Herndon's)
Confederate pension records, Arkansas
Ex-Confederate pension records, State Auditor's warrant books, Arkansas
Unfiled papers of Confederate soldiers, all states
Index to Confederate soldiers in units raised directly by the Confederate Government
Service records of Confederate General & Staff Officers, etc.
Confederate casualty lists & narrative battle reports, 1861-1865
Ex-Confederate amnesty papers, Arkansas
Confederate service records, Arkansas
History of Arkansas Confederate units
Confederate pension book index, Arkansas
Confederate miscellaneous pension records, Arkansas
1911 questionnaires, Confederate veterans
Consolidated index to compiled service records of Confederate soldiers
Inmates in the Arkansas Confederate Home
Service records: Confederate soldiers raised directly by the Confederate Government
Records of Confederate Naval & Marine personnel, all states