While Mary was with the 34th Indiana she fought many battles and was wounded three times. The 34th participated in the siege at New Madrid, Missouri on March 5-14, 1862, the siege and capture of Island #10 on the Mississippi River on March 15 to April 8, 1862, the capture of Fort Pillow on June 5, 1862, the Battle of Port Gibson on May 1, 1863, the Battle of Champion Hill on May 16, 1863 and the siege of Jackson, Mississippi on July 10, 1863.
In her last battle, she was wounded in the shoulder by a minie ball. This was the third time she had been wounded, but this time it was serious enough to require immediate medical attention. When the surgeon removed Mary's shirt to tend the wound he discovered that Pvt. James Wise was a woman. She was discharged after recovering.
Her discharge on the grounds of being a woman left her right to receive her pay in doubt. But Mary felt she had as much right to the pay as any male soldier and came to Washington to ask for her back pay. When the paymaster refused, President Lincoln "blazed with anger" and ordered the injustice rectified.
After her discharge in September 1864, she lived for a while with her friend Mrs. E.B. Gates and her husband, who was a captain in the Union army. Their home was at Lincoln Hospital in Washington, DC. While living there she met and fell in love with an army sergeant of the Veteran's Reserve Corps and married him at the hospital.The Washington Daily Morning Chronicle reported the story on September 30, 1824:
THE "BRAVE SOLDIER-GIRL"To the Editor of the Chronicle:
I beg leave to furnish THE CHRONICLE a further incident in the history of the soldier-girl who received her pay by the order of the President.
Miss Mary Wise found a good friend in, and a home with, Mrs. Captain E.B. Gates, at Lincoln Hospital where she soon made the acquaintance of Sergeant Forehand, of the Veteran Reserve Corps. This friendship soon ripened into affection, and the result was a marriage scene last evening at the above-named hospital, in which the soldier-girl and the sergeant were the principal actors. In other words, Miss Mary Ellen Wise (formerly James Wise, private of Company I, Thirty-fourth Regiment Indiana Volunteers), and Sergeant F. Forehand, of the Veteran Reserve Corps, were made man and wife--Uncle Sam thereby losing a brave soldier, and the sergeant finding a good wife. The ceremonies were performed by the chaplain of Lincoln Hospital, and were witnessed by quite a number of their soldier-friends.
Miss Mary has made many friends by her gentle and unassuming manners. They start for the New Hampshire home of the bridegroom to-morrow. May the now happy pair live to tell their grandchildren of the many hard-fought battles through which both have passed, and tell over the many amusing camp incidents so familiar to the sergeant and his companion, is the heart-felt wish of their friends. W.H.M.