George H. Gwin was born on September 15, 1832, in Blair County, Pennsylvania, to Alexander and Sarah Gwin. His father was a millwright who owned $700 of real estate in 1850. The family lived in Antis, Pennsylvania, until the 1850s, when they moved to Logan, Pennsylvania. His father died in the 1850s. By 1860, he was working as a farmer, and he owned $500 of real estate and $150 of personal property.
Gwin enlisted in the Union army on April 20, 1861, and he mustered in as a private in Company B of the 3rd Pennsylvania Infantry later that day. He mustered out three months later, on July 29, 1861. Then, on October 28, 1861, he received a commission as a 2nd lieutenant in Company B of the 76th Pennsylvania Infantry. He was wounded at Pocotaligo, South Carolina, on October 22, 1862, and he was promoted to 1st lieutenant the following day. The regiment took part in the assault on Fort Wagner in July 1863, and his brother Alexander was killed in action there. Gwin also took part in the Battle of Cold Harbor and the siege of Petersburg. He mustered out on November 28, 1864.
Gwin settled in Altoona after leaving the army. By 1870, he was working as a merchant, and he $2,000 of personal property. He married a woman named Ella in the 1870s, but she died sometime before 1900. He remained in Altoona for the rest of his life, and a local writer described him as “one of the city’s best known citizens.” By 1910, he was living with his brother James, and that year’s census described him as an “invalid soldier.” He died in Altoona of bronchopneumonia on January 10, 1914, and he was buried in his Civil War uniform “with all the honors of war.”