In 1798, the new Oaths issued by the Wexford Council had good effect. As Crown forces gathered on Wexford’s borders for the showdown, Nicholas Gray, Secretary of the Council, wrote on 16 June to Fr. Philip Roche, the new commander‑in‑chief. Gray was desperate for reinforcements for his Southern Army, which had almost melted away since the Battle of Ross:
Dear Citizen, We have, however, now issued orders, desiring all unmarried men to repair to camp immediately: we did so before, but they were not fully obeyed: at the present time particular obedience will be enforced, and we trust you will shortly find at your camp a number of fresh young fellows, as well appointed and provided as our best efforts can accomplish.
Gray’s words were no empty claim. Obedience was enforced with such effect that four days later this army was back in shape sufficiently to fight the Battle of Horetown, which lasted 4 1/4 hours when the shortage of gunpowder again forced the Wexford men to withdraw. The Southern Army was back in business, as Gray had predicted. The Republic’s writ still ran." 
Irish immigrants arrived in America during a time of political unrest. The Federalists cast themselves as "the Fathers of the People" as the Republicans posed as "the Friends of the People." Irish immigrants reinforced American republicanism to deprive the British empire of valuable labor and a potential soldier or sailor. "Republicanism represented more than a particular form of government. It was a way of life, a core ideology, an uncompromising commitment to liberty, and a total rejection of aristocracy." In 1803, the British Parliament limited the number of persons that any vessel could carry from Great Britain, reducing the Irish migration to America." 
In the War of 1812, as in other wars, the military relied heavily on immigrant recruits, which in 1812 meant the Irish. "The Irish had the desire to fight the British and due to poverty joined the army, navy or privateer service. The Irish recruits had a powerful incentive to deny Irish birth in recruiting records in case they were captured by the British. To control their own Irish troops, the British took a hard line against any subjects captured while bearing American arms. The British gave captured subjects a choice to enlist in their military or face trial and execution as traitors. Desperate for men, the British preferred enlistment of the Irish to their execution." 
Irish Rebels of the 1798 and 1803 rebellions in Ireland faced one another in Canada during the War of 1812. "In Upper Canada, the British feared of the loyalty of their own troops because most were Irish. After the rebellion of 1798, Ireland had become a prime recruiting ground for the British army. Due to poverty, recruits sought food, clothing, pay and a way out of Ireland. Irish were in the Forty-first, the Forty-ninth and the Royal Newfoundland Fencibles. The Forty-first foot included dozens of captured rebels of 1798, who had agreed to enlist to avoid the gallows." [6 ]
In this letter, Gray requests permission to recruit Irishmen, to fight the British for a third time -- in 1798 and 1803 in Ireland, and ultimately in America.
The following letter was sent by Nicholas Gray on Feb. 4, 1813, to General Armstrong, Secretary of War, Washington, D.C.:
I wish to have liberty to recruit a Regiment of Irish, to consist of Ten or Eighteen companies enlisted for the War, and to remain if possible on a permanent establishment.
I should also wish to be allowed to recommend such officers to it, as from education, and gentleman, and who from inclination, zeal, and patriotism, will ensure the good opinion of the government of the United States, and who have more or seen service.
It is my wish to interview with the views of any officer, wishing for the command of one of the Regiments to be raised. My object will be to enroll men who will not enter into any other Regiment, and to enlist the feelings and patriotism of Irish gentlemen, who otherwise would not think of joining the Army.
Veterans of the Irish rebellions of 1798 and 1803 made significant contributions to the War of 1812.
Irish-American officer Nicholas Gray was the army's inspector general 3rd Military District New York. Alexander Denniston commanded the Twenty-seventh Infantry, primarily composed of Irish recruits from New York City. Nicholas Gray described Denniston as "a Gentleman who has fought and beaten the Enemies of America in his native Country and now doubly are [his] enemies." Denniston had commanded a large body of pikemen during the 1798 Rebellion. Denniston recommended Nicholas Gray for appointment as colonel of the 27th Infantry Regiment in a letter to James Madison, dated February 12, 1815.
Nicholas Gray was also the private secretary to Governor Tompkins of New York, and the governor relied upon his advice. Tompkins wrote, Gray "has made Military matters his study and was Lieut General of the Irish patriots." In a letter dated Dec 30, 1811, postmarked Albany, New York, Daniel D Tompkins, governor of New York, informs Thomas Addis Emmet that "I have just visited with Nicholas Gray and find him recruiting very fast." 
In 1798 Nicholas Gray, an attorney from Wexford, Ireland, was active and zealous in swearing in United Irishman. The following information is taken from the book titled "The Emmet Rising in Kildare" by Irish writer Seamus Cullen. In his book a chapter is dedicated to Nicholas Gray. In the Emmet-led conspiracy in 1803, Gray and his brother-in-law, Henry Hughes, became members of the central leadership. Robert Emmet appointed Gray the general in charge of the Kildare rebels with full authority over the county. Cullen writes "It appears the name of the newly appointed Commander-in-Chief of the British forces in Ireland, General Fox, was the code name the rebels used for Nicholas Gray."
The Battle of the Thames, also called Battle of Moraviantown took place on October 5th, 1813 in the War of 1812. It was a decisive U.S. victory over British and Indian forces in Ontario, Canada, enabling the United States to consolidate its control over the Northwest. The U.S. victory helped catapult William Henry Harrison into the national limelight and eventually the presidency. Harrison [1773-1841] became America's ninth president, and served just one month in office before dying of pneumonia. Tecumseh, the Shawnee Chief. was killed in the Battle of Thames. After this battle, most of the tribes abandoned their association with the British. 
William Harrison's force numbered at least 3,500 infantry and cavalry. He had a small detachment of regulars from the 27th U.S. Infantry and five brigades of Kentucky militia led by Isaac Shelby. [14 On the American side was Brig. Gen. Lewis Cass, first colonel of the 27th Infantry, who, when he learned of Hull's surrender of Detroit, angrily broke his sword. Cass became colonel of the 27th United States Infantry Regiment on February 20, 1813.  Soon after, he was promoted to brigadier general in the Regular Army on March 12, 1813. The 27th's commander was Ohio-born Colonel George Paull. The fight on the American right flank was all over in less than 10 minutes. Paull's regulars had seized a 6-pounder, which had never been shot.
Irish-Americans were consistently on the front lines during the War of 1812 and were heavily invested for many reasons. Irish ancestors were an integral part of successfully defending America in what could have been a nation-ending conflict.
1. "Wexford in 1798: A Republic Before its Time" by Brian O'Cleirigh
2. "The Civil War of 1812" by Alan Taylor
3. Wikipedia Republicanism in the United States
4. "The Civil War of 1812" by Alan Taylor
5. "The Civil War of 1812" by Alan Taylor
6. "The Civil War of 1812" by Alan Taylor
7. National Archives Washington D.C.
8. "The Civil War of 1812" by Alan Taylor
9. "A Very Brilliant Affair" by Robert Malcomson
10. Public Papers of Daniel D. Tompkins, Governor of New York, 1807-1817, Volume 2
11. "The Emmet Rising in Kildare" by Seamus Cullen
12. Encyclopedia Britannica
13. Encyclopedia Britannica
15. Military History>
16 Military History