Mother-in-Law of the Army (San Antonio nickname)

San Antonio is home to Fort Sam Houston and other military bases. So many military men (including Dwight D. Eisenhower) married women while serving in the San Antonio area that the city has been called “Mother-in-Law of the Army” since at least 1917.
   
San Antonio has many other nicknames, including “Military City, USA.”
   
   
Wikipedia: Fort Sam Houston
Fort Sam Houston is a U.S. Army post in San Antonio, Texas. [2] Known colloquially as “Fort Sam”, it is named for the first President of the Republic of Texas, Sam Houston. Its approximate location is 29°26’56.69"N 98°26’56.04"W .
 
The installation’s missions include being the command headquarters for the Fifth U.S. Army (which became U.S. Army North as of October 2006), United States Army South, the Army Medical Command (MEDCOM) headquarters, the AMEDD Center and School, the Fifth Recruiting Brigade, 12th ROTC Brigade, U.S. Navy Regional Recruiting, the San Antonio Military Entrance and Processing Station, and the U.S. Naval School of Health Sciences, Bethesda Detachment. 
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Community connections
Throughout its existence, a close and harmonious relationship has prevailed between Fort Sam Houston and the City of San Antonio. The two have grown and matured together. The city often has been called the “mother-in-law of the Army” because so many soldiers including Dwight D. Eisenhower, met their future spouses here.
 
Google Books
Who’s Who Among the Women of San Antonio and Southwest Texas
A Blue Book and Directory and Year Book of the Women’s Organizations
edited and published under the direction of Miss Marin B. Fenwick, San Antonio, Texas
copyright 1917 by Elizabeth M. Newton
Pg. 7:
San Antonio is familiarly called the mother-in-law of the army and an effort has been made to list the girls who have married in the army.
 
Google Books
Texas: A Guide to the Lone Star State
by the Writers’ Program of the Works Progress Administration of Texas
New York, NY: Hastings House
1940
Pg. 326:
Small wonder the city is known in some circles as “the mother-in-law of the army” because so many of its personnel have married while serving in San Antonio.
 
Google Books
The Army Wife
by Nancy Brinton Shea
New York, NY: Harper & Brothers
1941
Pg. 19:
San Antonio is affectionately called “The Mother-in-law of the Army,” owing to the fact that so many Texas girls marry Army officers.
 
Google Books
Randolph Field: A History and Guide
by the Writers’ Program of the Work Projects Administration of Texas
New York, NY: The Devin-Adair Company
1942
Pg. 85:
... have helped to build the impressive total of military-civilian marriages that has caused San Antonio to be called “the Mother-in-law of the Army.
   
Time magazine
San Antonio Does Its Part
Monday, Feb. 21, 1944
   
All U.S. troops overseas are not Texans. But the frequency of Texas addresses in dispatches from the battlefronts does indicate a fact of which all Texans are proud: a lot of them are.
 
Some figures compiled in San Antonio last Week indicated just how much one Texas city had contributed to the fighting of the war:
 
From a population (1940) of 319,010, the metropolitan area of San Antonio furnished the armed forces 51,000, including many sons-in-law. (San Antonio, longtime home of Kelly and Randolph Fields and Fort Sam Houston, is called “mother-in-law of the Army.”)
   
Google Books
Early Days in Texas
by Felda Davis Shanklin
San Antonio, TX: The Naylor Company
1954
Pg. 15:
“They called the new field ‘the mother-in-law of the Army,’” Gayle remembered.
 
14 April 1955, Dallas (TX) Morning News, part 1, pg. 7 ad:
May HOLIDAY magazine salutes SAN ANTONIO
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Learn how San Antonio won the name “Mother-in-law of the Army.”
 
13 February 1965, Dallas (TX) Morning News, “City’s Role in Space, Air Industry Lauded,” section 1, pg. 9:
“They used to call San Antonio the mother-in-law of the Army,” he joked. “Now I guess you’d say Dallas is the center of the aviation industry.”
 
19 October 1967, San Antonio (TX)

, “Ft. Sam Houston Oldest Military Base in S. A.,” pg. 92-NC, col. 3:
By 1890 much of the frontier flavor of the Post of San Antonio was gone. Daily band concerts and parties brought the lovely San Antonio belles and the handsome Army officers together in such numbers that the city was nick-named “Mother-in-Law” of the Army.
 
7 April 1968, Oakland (CA) Tribune, “The Alamo—And Much More” by Mort Cathro, pg. 43, col. 1:
SAN ANTONIO—San Antonio (the Alamo City, the Manena Community, the Capital of Occupied Mexico, the Mother-in-Law of the Army, the 15th largest city in the United States) would be a delightful place to visit even if it weren’t for the HemisFair.