The 1850 & 1860 Federal census record William’s birth date as about 1843. He is listed as William P. in 1860

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1850 United States Federal Census about A Stewart
Name: A Stewart
[Armstrong Stewart]
Age: 31
Birth Year: abt 1819
Birthplace: Georgia
Home in 1850: District 28, Benton, Alabama
Gender: Male
Family Number: 525
Household Members:
Name Age
A Stewart 31 Farmer
Mary Stewart 31
W L Stewart 7
J A Stewart 5
S J Stewart 3
D M Stewart 0

1832--Benton County was formed 18 December 1832 from the Creek Cession.
1858--Renamed 29 January 1858 to Calhoun County.

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1860 United States Federal Census about A A Steward
Name: A A Steward
[A A Stewart]
Age in 1860: 40
Birth Year: abt 1820
Birthplace: Georgia
Home in 1860: Township 12 Range 10, Calhoun, Alabama
Gender: Male
Post Office: Ladiaga
Household Members:
Name Age
A A Steward 40 Farmer
Mary Steward 40
William P Steward 17
Julian Steward 15
Sarah J Steward 13
Amanda M Steward 10
Lawson Steward 7
John Steward 5
Ross Steward 3
Adaline Steward 1

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This might be William

W P. Stewart
Residence was not listed;
Enlisted as a Private
"I" Co. AL 35th Infantry

Sources used by Historical Data Systems, Inc.:
- Index to Compiled Confederate Military Service Records

The Thirty-fifth regiment was organized at La Grange in April,
1862

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Recruit, examined for Capt. Chisholm’s Company Alabama Volunteers at Camp of Instruction, La Grange, Alabama, March 31, 1862

Corporal W. P. Stewart, enlisted March 22, 1862 at Florenco, Alabama, died November 2, 1862

William Stawart, Private, enlisted April 15, 1862 at Florence, Lauderdale County, Alabama. Died at Holly Springs, Miss. November 3, 1862. Widow Elizabeth Stewart

M311 Compiled Service Records of Confederate Soldiers Who Served in Organizations from the State of Alabama