Here is the original Federal oath, which may or may not be the same as Hercules was administered.

On December 3, 1863, President Lincoln offered in the Proclamation and Reconstruction of Amnesty, a pardon to all citizens with some exclusions, who would take the oath of loyalty to the United States. That also, as soon as one-tenth of the citizens had taken the prescribed oath there in any state, there could be re-established a state government.

The oath reads:

“I, (repeat full name), do solemnly swear, in the presence of almighty God, that I will henceforth faithfully support, protect, and defend the Constitution of the United States, and the Union of the States thereunder, and that I will, in like manner, abide by and faithfully support all Acts of Congress passed during the existing rebellion with reference to slaves, so long and so far as not repealed, modified, or held void by Congress, or by the decision of the Supreme Court; and that I will, in like manner, abide by and faithfully support all proclamations of the President made during the existing rebellion having reference to slaves,
so long and so far as not modified or declared void by decision of the Supreme Court, so help me God.”
http://www.rootsweb.ancestry.com/~ardesha/amnesty.htm
…………

It was an eventful day when the young Lt., Uriah Allison, marched through the town of Kingston, with his fifers & drummer boy. He had been appointed 2nd Lieut. of the 8th U. S. Inf., March 15, 1812, had reported at Knoxville by an order signed by Capt. John A. Rogers and had been instructed by Edmund P. Gaines, Lt. Col., U. S. Infty., to make all necessary provisions for recruits.

The men and boys gathered about the fifers and drummer in front of the Court House, while the women and children watched in the background with excitement. Bright new U. S. dollars lay upon the head of the drum, every man who stepped up took a dollar became a volunteer in the War of 1812. Among the first to take a dollar from the drum was Jeremiah Buchanan, and three of his sons. Hercules, Moses, and Jeremiah Jr. They were paid $16 per month. (Taken from Roane County, TN Military Records)
http://trees.ancestry.com/tree/42738772/person/19906557338/story/950d2540-ab59-416f-bf1f-228b6725de73?src=search

……..

Name: Hercules Buchanan
Birth Date: 22 Jul 1792
Death Date: 16 Apr 1868
Cemetery: Buchanan Cemetery
Burial or Cremation Place: Stewart County, Tennessee, USA
http://www.findagrave.com/cgi-bin/fg.cgi?page=gr&GRid=19462681&ref=acom