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Officers of U. S. Army Who Left after November 1, 1860 and Joined the Confederate Army

Last Name	First / Middle Name	Rank / Unit	Date Left	Comments

Van Dorn	Earl	maj 2 cav	31 Jan 1861	graduate of the U.S. Military Academy
Villepigue	John B.	1 lt 2 drgs	31 Jan 1861	graduate of the U.S. Military Academy

Source: Historical Register and Dictionary of the United States Army 1789 - 1903

Some additional excellent resources for your research are:

Civil War Pension Index
Maryland Settlers and Soldiers, 1700s-1800s
Interment.net ~ Cemetery Transcriptions on the net.
Ancestry.com ~ A huge compilation of databases some of which are free and some of which require a paid subscription.
Kindred Konnections ~ Search the World's Largest Pedigree-linked Database.