Question: Which Union Civil War General with initial M that resigned fought during the Mexican-American War ?

text: List of American Civil War generals (Union)
Union generals -- M

The following lists show the names, substantive ranks, and brevet ranks (if applicable) of all general officers who served in the United States Army during the Civil War, in addition to a small selection of lower-ranked officers who received brevets as general officers; while some 1,600 officers received or were nominated for brevets as general officers in the course of the war (or immediately following it for service during the war), only a small selection is listed here; only those who were killed in action, served as department heads within the army, had revoked or incomplete appointments or became U.S. President are listed here. In addition to their names and ranks, there is a small set of notes after every entry listing Medal of Honor or Thanks of Congress citations, West Point graduation dates, important political or Army offices held, retirements or deaths during the war (whether in action or other means), notable relations, rejections or expiration of appointments, or unique facts pertaining to this article (i.e. youngest general, last surviving general, etc. ); for all other information on their lives and accomplishments, please refer to their individual entries. If available, ranks are followed by the to rank from dates (i.e. the date on which the commission is effective) rather than the date of appointment or confirmation, which were generally months if not years later; this is particularly true in the case of brevets, most of which were granted after the war between 1866 and 1869. Note on abbreviations:
Name Substantive Rank Notes
McArthur , John Brigadier general , USV ( March 21 , 1862 )
McCall , George Archibald Brigadier general , USV ( May 15 , 1861 ) USMA , 1822 Resigned March 31 , 1863
McCleery , James Major , USV ( 1865 ) U.S . Congressman from Louisiana ( 1871 )
McClellan , George Brinton Major general , USA ( May 14 , 1861 ) USMA , 1846 General-in-Chief ( November 1 , 1861 - July 22 , 1862 ) Relieved of duty November 7 , 1862 Resigned November 8 , 1864 Governor of New Jersey ( 1878-1881 )
McClernand , John Alexander Major general , USV ( May 21 , 1862 ) Resigned November 30 , 1864 U.S . Congressman from Illinois ( 1843-1851 , 1859-1861 )
McConihe , John Colonel , USV KIA , Battle of Cold Harbor ( June 1 , 1864 )
McCook , Alexander McDowell Major general , USV ( July 17 , 1862 ) Highest-ranking of the fourteen Fighting McCooks Brother of Daniel McCook , Jr. , Edwin Stanton McCook , and Robert Latimer McCook Cousin of Anson George McCook and Edward Moody McCook
McCook , Daniel , Jr Brigadier general , USV ( July 16 , 1864 ) DOW , Battle of Kennesaw Mountain ( w. June 27 , 1864 , d. July 17 , 1864 ) Brother of Alexander McDowell McCook , Edwin Stanton McCook , and Robert Latimer McCook Cousin of Anson George McCook and Edward Moody McCook
McCook , Edward Moody First Lieutenant , USA ( May 8 , 1861 ) Brigadier general , USV ( April 27 , 1864 ) U.S. minister to Hawai ' i ( 1866-1868 ) Territorial Governor of Colorado ( 1869-1873 , 1874-1875 ) Brother of Anson George McCook Cousin of Alexander McDowell McCook , Daniel McCook , Jr. , Edwin Stanton McCook , and Robert Latimer McCook
McCook , Robert Latimer Brigadier general , USV ( March 21 , 1862 ) DOW sustained near Huntsville , Alabama ( w. August 5 , 1862 , d. August 6 , 1862 ) Brother of Alexander McDowell McCook , Daniel McCook , Jr. , and Edwin Stanton McCook Cousin of Anson George McCook and Edward Moody McCook
McDowell , Irvin Brigadier general , USA ( May 14 , 1861 ) Major general , USV ( March 14 , 1862 ) USMA , 1838
McGinnis , George Francis Brigadier general , USV ( November 29 , 1862 )
McIntosh , John Baillie Second Lieutenant , USA ( 1861 ) Brigadier general , USV ( July 21 , 1864 ) Brother of General James McQueen McIntosh , CSA
McKean , Thomas Jefferson Brigadier general , USV ( November 21 , 1861 ) USMA , 1831
Mackenzie , Ranald Slidell Captain , USA Brigadier general , USV ( 1864 ) USMA , 1862 Nephew of Confederate diplomat John Slidell
McKinstry , Justus Brigadier general , USV ( September 2 , 1861 ) USMA , 1838 Dismissed from service for corruption , January 28 , 1863
McLean , Nathaniel Collins Brigadier general , USV ( November 29 , 1862 ) Resigned April 20 , 1865
McMillan , James Winning Brigadier general , USV ( November 29 , 1862 ) Resigned May 15 , 1865
McNeil , John Brigadier general , USV ( November 29 , 1862 ) Resigned April 12 , 1865
McPherson , James Birdseye Brigadier general , USA ( August 1 , 1863 ) Major general , USV ( October 8 , 1862 ) USMA , 1853 KIA , Battle of Atlanta ( July 22 , 1864 ) Only Union Army commander to be KIA