After the secession of Tennessee and beginning of the Civil war, George Maney enlisted in the Confederate army as a captain in the 11th Tennessee Volunteer Infantry. On may 6, 1861 he was promoted to Colonel of the 1st Tennessee. He served first with Robert E. Lee at the battle of Cheat Mountain and later under Stonewall Jackson at Bath and Romney.
He asked for reassignment to Tennessee. As an officer in the Army of Tennessee, he participated in the Battle of Shiloh and was promoted on April 16, 1862 to Brigadier General, He led his brigade in the Battles of Perryville, Chickamauga and Murfreesboro. In November 1863 he was wounded severely in the arm during the Chattanooga Campaign. He was on medical leave for rest of the year.
In 1864, Maney commanded a division in William J. Hardee's corps during the Atlanta Campaign. He was captured in August and later released. Maney surrendered following the Carolina Campaign and was paroled on May 1, 1865 at Greensboro, N.C.
After the war he returned to Tennessee. He was President of the Tennessee and Pacific Railroad in 1868 and held that position for 9 years. He became active in politics and joined the Republican Party. He did a lot to help reconciliation efforts during Reconstruction.
During the presidential administrations of James Garfield, Chester Arthur and Benjamin Harrison, Maney was appointed as ambassador to various counties in South America. He was U.S. Minister to Columbia 1881-1882, Minister/Resident/Consul General to Bolivia from Nov. 1882 to June 1883. He spent 4 years, 1890-1894 as the U.S. Ambassador to Uruguay and Paraguay.
He died in Washington D,C. on Feb 9, 1901, and is buried in Mount Olivet Cemetery in Nashville, Tennessee.