Originally a Republican, he oversaw the forceful passage of the post-American Civil War constitutional amendments while he was a member of the Indiana Senate.

[1] Only a month after he opened a law office the American Civil War began, and Gray set out to raise a company of volunteers.

He led his regiment against forces under Confederate General John Hunt Morgan near Munfordville, Kentucky in December 1862.

[2] Gray began to become moderately wealthy and expanded his business interest into grain processing and banking.

In his first run for office, he competed against George Washington Julian in the Republican primary, hoping to become a candidate for Congress, but was defeated in 1866.

[2] When the final amendment was submitted for ratification, the Democrats attempted to leave the Senate to deny the body quorum.

After some time passed, and they refused to return to the floor, Gray ordered the clerks to record the Democrats present, but abstaining from voting.

[2] Gray was appointed by President Ulysses Grant and confirmed by the United States Senate to serve as consul to St. Thomas the same year, but he declined the office and wrote a letter to President Grant saying he was repulsed by the corruption of his administration.

He attended its national convention in 1876, but after the party made no gains at the polls that year, he decided to become a Democrat.

[3] In 1876, Gray was nominated to run for Lieutenant Governor of Indiana on the ticket with James D. Williams in hope of gaining the vote of disaffected Republicans.

He was widely criticized by the minority party for creating gerrymandered districts to weaken their electoral base.

Knowing that he could probably sway one of the Greenbacks to vote for his bid for the United States Senate, Gray began to attempt to have his name entered as a candidate.

He also successfully had the White Caps, a group involved in vigilantism in the southern part of the state, investigated and broken up.

[7] Barred by the Constitution of Indiana from serving a consecutive term, Gray retired from office and returned to his law practice.

[7] Gray was one of the Democratic vice presidential candidates in 1888, but he lost the nomination to Allen G. Thurman, primarily because his enemies again brought up his actions while a Republican.

[8] He returned to his law practice, and because of all of the situations he found himself in, he gained the derisive nickname "Sisyphus of the Wabash."

He was again almost nominated to run for vice president again in 1892, but was defeated again after his opponent ascended the podium to retell the story of his actions in the amendment ratification twenty years earlier.

[9] The President of Mexico ordered all the flags flown at half staff in Gray's honor and a full division of the Mexican Army escorted Gray's body back to the border where he was transferred by parcel post to Indianapolis to lie in state.