Date of birth was given as “Jul 1845” on the 1900 census. Grave marker at the Kicaster Cemetery gives 27 Apr 1844.
1181 According to a family tradition (Mrs. Mae Swift), “William H. Davis, son of James Davis, served in the Cibolo Guards of the Confederate Army.  James Davis came to St. Hedwig in 1856 on the Cibolo Creek.  He and his oldest daughter Madora Ann and William H. Davis with his twin sister Martha lived on 840 acres of land.  As the family was travelling from Mississippi through Arkansas, James Davis’ wife died with the twins were born.”  
Note added June 22, 2011:  This tradition is probably wrong as the 1850 census (see below) shows that the family lived in Arkansas and had probably been there for some time since Medora was born in Arkansas in 1840.Per 1867-1869 Registration of Voters, Bexar County, TX: Wm. H.H. Davis on November 17, 1869 had lived in the state of Texas for 15Y and the County of Bexar for 12Y.
1850 Census of Douglas, Arkansas Co AR
Name                       	Age
S H Davis                  	53, m, farmer, KY
Charles Davis          	28, m, farmer, KY
Edward Davis            	23, m, farmer, KY
John Davis                	20, m, farmer, KY
Samuel Davis            	17, m, farmer, KY
Medora Davis           	10, f, AR
William Davis          	  4, m, AR
Martha Davis             	  4, f, AR
1860 census San Antonio, Bexar Co TXName         			AgeS H Davis        	        64	m w	farmer	b KY	
Sarah J Davis      		28	f w		        b MS	
W H H Davis      		15	m w		        b ARN P C Davis      		15	f w		        b AR
Lucy R Davis     		  4	f w		        b TX
1880 Wilson Co TX censusName         			AgeWilliam H. H. Davis	34			MS KY --Phoebe Davis    		22	wife		MO TN TN
Samuel J. Davis       	  2	son		TX MS MO
Chas. R. E. Tyner      	12	nephew	TX -- MS
Thomas Mc Cage       	16	employee
1900 Census of Justice Precinct 7, Bexar, TexasWilliam H. S. Davis, Head, w, m, July 1845, 54, married 23 years, Ark, KY, KYPhoebe L. Davis, Wife, w, f, Apr 1857, 43, married 23 years, mother of 8 children, 6 living, MO, TN, TN
Thomas J. Davis, Son, w, m, May 1887, 13, single, TX, MO, TN
David F. Davis, Son, w, m, Nov 1890, 9, single, TX, MO, TN
Daisy M. Davis, Daughter, w, f, Nov 1890, 9, single, TX, MO, TN
James S. Davis, Son, w, m, June 1893, 6, single, TX, MO, TN
1910 Census of San Antonio Ward 4, Bexar, TXWilliam H. Davis, Head, m, w, 64, married 32 years, Ark, MS, MSPheobe L. Davis, Wife, f, w, 53, married 32 years, mother of 8 children, 6 living, MO, TN, TN
David F. Davis, Son, m, w, 19, single, TX, Ark, MO
Daisy M. Davis, Daughter, f, w, 19, single, TX, Ark, MO