Here are some possibilities:
The following Alfred Stevens who died 2-2-1919 in Tangipahoa Parish could possibly be the same Alfred Stevens of the 18th Battalion of Calvary:
Name: Alfred Stevens
Death Date: 2 Feb 1919
Estimated Birth Year: 1833
Age: 86 years
Parish: Tangipahoa
Certificate Number: 2631
Volume: 5
Title: Louisiana Statewide Death Indeces 1900-1929
Source Information:
Ancestry.com. Louisiana Statewide Death Index, 1900-1949 [database on-line]. Provo, UT, USA: The Generations Network, Inc., 2002. Original data: State of Louisiana, Secretary of State, Division of Archives, Records Management, and History. Vital Records Indices. Baton Rouge, LA, USA.
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Also, census records of Tangipahoa Parish show an Alfred or Alford Stevens who married someone named Nancy as follows:
Alfred Stevens--67
Nancy C Stevens--63
Maria Stevens--38
Robert E Lee Stevens--27
Carrie E Stevens--22
Steven R Stevens--25
Rosalie Stevens--18
Source Citation: Year: 1900; Census Place: Police Jury Ward 4, Tangipahoa, Louisiana; Roll: T623 583; Page: 10B; Enumeration District: 91. (The index at Ancestry.com incorrectly links his name to image 20, but he actually appears on image 19.)
Source Information:
Ancestry.com. 1900 United States Federal Census [database on-line]. Provo, UT, USA: The Generations Network, Inc., 2004.
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Alfred Stevens--77--widower
Maria Stevens--40
Rosa Stevens--25
Robert E Stevens--36
Source Citation: Year: 1910; Census Place: Police Jury Ward 4, Tangipahoa, Louisiana; Roll: T624_532; Page: 8B; Enumeration District: 112; Image: 275.
Source Information:
Ancestry.com. 1910 United States Federal Census [database on-line]. Provo, UT, USA: The Generations Network, Inc., 2006.
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Alford Stevens--28
Nancey Stevens--24
Eliza D Stevens--5
Leanda Stevens--4
Sarah Stevens--3
Berlin Stevens--1
Source Citation: Year: 1860; Census Place: , Livingston, Louisiana; Roll: M653_413; Page: 0; Image: 237.
Source Information:
Ancestry.com. 1860 United States Federal Census [database on-line]. Provo, UT, USA: The Generations Network, Inc., 2004.
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The above Alfred or Alford Stevens also appears on the Louisiana census records of 1850, 1870, and 1880. This Alfred Stevens could possibly be the same Alfred Stevens who died 2-2-1919.
Good luck in your search.