Andrew had an interesting military career.

U.S. Civil War Soldiers, 1861-1865 about Andrew J. Pemberton
Name: Andrew J. Pemberton
Side: Union
Regiment State/Origin: Pennsylvania
Regiment Name: James' Indpt. Co., Pennsylvania Cav. (Philadelphia City Troop.)
Regiment Name Expanded: James' Independent Company, Pennsylvania Cavalry (Philadelphia City Troop)
Rank In: Private
Rank In Expanded: Private
Rank Out: Private
Rank Out Expanded: Private
Film Number: M554 roll 95

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U.S. Civil War Soldiers, 1861-1865 about Andrew J. Pemberton
Name: Andrew J. Pemberton
Side: Union
Regiment State/Origin: Pennsylvania
Regiment Name: 23 Pennsylvania Inf.
Regiment Name Expanded: 23rd Regiment, Pennsylvania Infantry
Company: F
Rank In: Second Lieutenant
Rank In Expanded: Second Lieutenant
Rank Out: Second Lieutenant
Rank Out Expanded: Second Lieutenant
Film Number: M554 roll 95
Source Information:
National Park Service. U.S. Civil War Soldiers, 1861-1865 [database on-line]. Provo, UT, USA: Ancestry.com Operations Inc, 2007.

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A J. Pemberton

Enlisted on 9/8/1863 as a 1st Lieutenant.
On 9/8/1863 he was commissioned into "E" Co. MD 3rd Cavalry
He was discharged on 6/8/1864
Promotions:
* Capt 9/23/1863

Sources used by Historical Data Systems, Inc.:
- Maryland Volunteers, War of 1861-65

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Andrew J. Pemberton
Enlisted on 2/24/1865 as a 1st Lieutenant.
On 2/24/1865 he was commissioned into "L" Co. PA 5th Cavalry (65th Vols.)
He was Mustered Out on 8/7/1865 at Richmond, VA
(Absent sick)

Sources used by Historical Data Systems, Inc.:
- History of Pennsylvania Volunteers, 1861-1865

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Andrew J. Pemberton, age 32, 1st Lieutenant, Company E, 3rd Maryland Cavalry, USA, mustered in September 8, 1863, mustered out and in as Captain September 23, 1863 at Baltimore, Md., dismissed from the service June 8, 1864 by order of Maj. Gen. Canby,

"Camp 3rd Md. Cavalry
Morganza, La. June 1864

Lt. Col. C. B. Irwin
A. A. General Dept. of the Gulf
Col.
I have the honor to tender my resignation and unconditionally resignation as Capt. of 'E' Squadron 3rd Md. Cavalry a higher position is offered me (by private letter) in the army to which I formerly belonged, it is but natural that I should wish to be with the army of the Potomac having served with it from the time it was first formed as a Lieut. of 23rd P. V. Infantry. I have every prospect of a position to which I am more suited than that of Capt. of Cavalry which position I am confident I can not fill with credit to myself or of any benefit to the service. I feel confident that Richmond is about to fall and it is but natural that I should wish to be there having striven to reach that point up to the battle of Chancellorsville. I therefore cannot be blamed when I confess that my heart and interest is not here, but in the East. Under these circumstances I earnestly request that my resignation may be accepted.
I have the honor to be
Sir, very respectfully,
Your obt. Sevt.
A. J. Pemberton
Capt. E Squadron
3rd Md. Cavalry"

M384: Compiled Service Records of Volunteer Union Soldiers Who Served in Organizations from the State Of Maryland

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Andrew J. Pemberton, Private, James Independent Company, Pennsylvania, Cavalry (Philadelphia City Troops), No records

Andrew and his brother Clifford enlisted April, 1861
[LGen. Pemberton's autobiography]

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Andrew J. Pemberton, 1st Lieutenant, Company D, 3rd Pennsylvania Cavalry, see also 5th Pennsylvania Cavalry

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Andrew J. Pemberton, 1st Lieutenant, Company L. 5th Pennsylvania Cavalry, see also 3rd Pennsylvania Cavalry

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Andrew J. Pemberton, 2nd Lieutenant, Company F, 23rd Pennsylvania Infantry

M554: Index to Compiled Service Records of Volunteer Union Soldier Who Served in Organizations from the State of Pennsylvania

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His widow Mary J. Pemberton filed for a Widow's pension Application No. 824 477 from Pennsylvania March 17, 1905 referencing his service in the 3rd Md. Cav. and 23rd Pa. Inf.
National Archives and Records Administration. U.S., Civil War Pension Index: General Index to Pension Files, 1861-1934 [database on-line]. Provo, UT, USA: Ancestry.com Operations Inc, 2000.