In 1812, in the first summer of America's 'second War of Independence' with Britain, a valuable survey describing the whole Niagara Frontier was made by Irish immigrant Nicholas Gray, a colonel in the United States Army.
Pictured, an image that is believed to be that of Nicholas Gray.
In Gray's report to General Van Rensselaer, he details the British defenses at the border between Ontario, in British North America, and New York state. Gray points out the places an American invasion would be impossible and places where a crossing might be achieved. Included in his report was a full-page pen-and-ink map with the possible crossings of the Niagara River, from Lake Erie to Lake Ontario, marked.
The report was datelined, Lewiston, August 31, 1812, suggesting that the eventual attack was made at Lewiston because of the opinions given in this document, as Gray enlarges on the possibility of crossing there, and describes the approaches to Queenstown. He noted the distance from there of the British main force. The Battle of Queenston Heights was fought six weeks after the date of this document. 
Fort Gray, named after the colonel, contained two 18-pounder long guns, two 6-pounder field guns and two 5.5-inch mortars, all near the landing stage, which helped support the American crossing of the Niagara River during the Battle of Queenston Heights, fought October 13, 1812.
Gray arrived in the Niagara Frontier on July 18, and stated the enemy had thrown up batteries on the south and north approaches to Queenston. "The enemy unfortunately have the commanding ground everywhere," he reported. "The absolute want of all sorts of working tools has prevented the troops from taking measures absolutely necessary to their protection. They have been in the want of everthing. The tents and supplies have not as yet arrived, but also expected is some artillery."
In an August 20 letter to one Mrs. Codd, likely an Irish immigrant and relative living in Buffalo, N.Y., Nicholas stated: "I sleep every night almost at the muzzle of the British Cannons. I have built three batteries which have placed the quarters of our troops in security -- one at Lewiston, one at Black Rock here, and one opposite Fort Erie. The country around here is beautiful and picturesque. I write you on the bank of the Niagara River, two miles or so from Lake Erie."
(Below: map of the area around Fort Gray)
Gray continued: "I have been highly flattered by receiving the thanks of the Generals on the lines for the exertions I have made in making their situation secure. General Van Rensselaer feels secure even under the guns of the enemy at Queenston, and Colonel Swift, who commands here, has no terror, as he has a battery or two of his own. The inhabitants of Buffalo wish for a one-gun battery to protect their town.
"From the battery located at Brown's Point, about two miles from Queenston on the Canadian side, Oct 14th, 1812. About half an hour before daylight yesterday morning, Tuesday, the 13th, October. I heard a heavy Cannonading from Fort Gray, situated on the height of the mountain on the American side and commanding the town of Queenston."  
(Pictured: The Battle of Queenston Heights, by James B. Dennis. From the Library and Archives Canada.)
According to author Peter Porter in his book "Landmarks on the Niagara Frontier; a Chronology," when the War of 1812 was declared, there were only three United States forts on this frontier: Niagara, in an "excellent state" at the Niagara's mouth; the Black Rock Blockhouse; and Schlosser, which was "valueless."
At this same period, according to Porter, the only fortifications on the Canadian shore was Fort George, a strong fort at the Niagara's mouth, and Fort Erie at its source.
In October 1812, hostilities erupted along the Niagara River, and it was reported that there were 100 cannons on the Canadian frontier, brought in by the British anticipating war. This explains how they could establish so many batteries along a very sparsely settled frontier.
According to Porter:
After the declaration of war in August 1812, the Americans built Fort Tompkins [or Adams as it was also called] on the top of the bluff, at the bend of Niagara Street, in the city of Buffalo. It was a rather pretentious earthwork mounting seven guns, and was the largest of several fortifications erected during that summer along the shore in the villages of Buffalo and Black Rock -- the others being known as 'batteries' and enumerated further on. The Americans at this time also built, on the brow of Lewiston Mountain, near the edge the gorge, a substantial earthwork called "Fort Gray" after its builder, Nicholas Gray.
(Pictured: The death of General Brock at the Battle of Queenston Heights by John David Kelly - National Archives of Canada)
The first actual hostilities of that war along this frontier occurred on October 13, 1812, in the battle Queenston Heights; on the same day Forts Niagara and George bombarded each other, and Forts Tompkins and Erie did likewise. A month later Fort George, and several batteries that had been constructed near it, again opened fire on Fort Niagara; that fort, with its adjacent batteries, replied in kind. It is recorded that 2,000 cannon balls were fired at Fort Niagara, within the space of one day, besides 180 shells. That fort's reply, while spirited, was not so great numerically, but was more effective. A cannonade lasting a whole day, during which fully 3,000 cannon balls were fired, at a range of not over three-quarters of a mile, in which only about half a dozen men were killed and very few wounded. As a result of which neither fort was seriously damaged. "But it was war -- bitter war -- at close range," according to a letter found in the archives of the Army adjutant general. 
At this same point in time, Gray's youngest brother, Loftus, was a member of the British Rifle Brigade. The Rifle Brigade was a change in tactical doctrine for the British. They needed to think for themselves and also were chosen for being better shots. Loftus joined the Brigade in 1800 the year the 95th. Rifles were formed. They dressed in green Jackets with black belts and were seen as the special forces of the day. Because of the green jackets, the French referred to them as "the Grasshoppers." The men of the 95th were equipped with the accurate Baker Rifle. These soldiers were trained to fight in pairs and use the ground for cover from enemy positions. Loftus Gray of the Rifle Brigade was severely wounded at the Battle of Tarbes, France, in 1814. He was wounded in the lip and part of his heal was missing. Lieut. Col. Loftus Gray was appointed Governor of Pendennis Castle on July 25, 1832, and died on August 20, 1835.
(Pictured: The Brock Memorial on Queenston Heights)
Governor Tompkins had sent his personal assistant to the Niagara Frontier to perform various duties. Gray was an experienced Irish engineer, artillerist and surveyor. Nicholas Gray also was Inspector General of New York 3rd District. In a letter dated February 5th,1814, to the Secretary of War John Armstrong, Gray states: "I have been ordered by the Inspector General office Washington for the arrest and trial of Doctor Ackerly, Hospital Surgeon. Directing me to take proper measures to present charges and furnish the list of witnesses. If you are pleased to allow me the aid of a Lawyer. With my multiplicity of duties it will enable me to discharge more punctually the duties of the district."
In a letter dated Feb 10, 1814, to the Secretary of War John Armstrong Gray states "a great and beneficial change has taken place in the Military Hospital. More could be done but for the clashing of the departments. With the arrest of Dr. Ackerly, I have drawn upon my back some powerful opponents. My hopes are rested Sir, with you and the government -- and my consolation is having impartially done my duty."
On Feb 13, 1814, in another letter to the Secretary of War John Armstrong, Gray continues: " I am induced to write you this letter, from the ground that Doctor Ackerly and his friends have taken with relation to the pending Court Martial. I have heard from undoubted authority, that an objection to my competency as prosecutor, is to be made on the score of my not being a Naturalized Ctizen of these States. Not withstanding my appointment by The President and Senate. In a few months I shall have the honor to be entitled to naturalization, by the laws of this country. I hold as Inspector General a situation of the highest trust. I should humbly suppose, in case I do not betray that trust or neglect the duties of my office, that, I am entitled to the protection of the Executive, and as so entitled, cannot fail of meeting its entire support. I beg laws to observe, that I am hourly threatened by the host of friends and family connections, of Doctor Ackerly. I feel confident of protection in the discharge of my duty. I wish to serve the goverment of my adopted Country faithfully and guard the rights of the invalid soldiers, who fight her battles, and whose speedy return to duty, is of so much consequence at this moment to the district."
To the Secretary of War John Armstrong from Inspector General Office April 23, 1814, New York 3rd District. "Some time since, I have the honor to transmit to you, by order of Brig General Porter, a list of the rejected recruits of this district and a return of such Soldiers as were unfit from disease, for service. It has been my practice in all cases to have with me an Army Surgeon to examine the recruits and to reject such as we found unfit for the service, but no man has been rejected who ought to be retained. The object of this letter is to state to you Sir, the awkward situation in which I have been placed by the General Command of this district. Soon after the list of Soldiers I have mentioned to you, had been returned to Headquarters, General Dearborn ordered a review of the rejected recruits, and as I am informed, authorized Colonel Bogarden to use his own discretion in retaining such as he thought proper. My information is from the Colonel who at Sandy Hook, took the role of these rejected men, and separated from it those he thought fit to retain. I argued on the spot against this irregularity and think I have now exonerated myself from consequences of the transaction. Sir, to say that so long as I did my duty I should have your support."[7 ]
Honorable John Armstrong, Aug 6, 1814: " I have the honor to again assist you, that this morning I have been ordered under arrest by the Commanding General, upon charges of which a copy is forwarded by Col. Denniston and which all originate in Malice against me for the strict performance of my duties. I only desire impartial men upon the court and such as are not frantic enough to accuse the government for having employed me."  The 3rd Military district of the U.S. Judge Advocate's office: "Sir, the charges against Col. Nicholas Gray Inspector General of this District having been withdrawn by the prosecution, Charles Humphrey, and for discharging the prisoner from his arrest. Henry Wheaton Judge Advocate."
Col. Alexander Denniston was a native of County Longford, Ireland. Alexander along with his brother Hans were United Irishmen who like Nicholas Gray, led rebels in the Irish rebellion of 1798. Nicholas had a list of witnesses in his defense for the Court Martial trial who also wrote letters of endorsement. A letter to James Monroe, Secretary of State, delivered by Gray's friend General Porter December 22, 1814: "Gray writes it would be an honor to fill a position of importance and respectability. No man can perform the duties of Inspector General, without making many enemies -- losing many friends and gaining very few." 
In a letter to President James Madison, March 1st, 1815. Memorial of Col. Nicholas Gray - That your, memorialist has been employed since the commencement of the War in the service of the United States. That he served on the Niagara Frontier in the year 1812 as a volunteer, part of the time in the capacity of Engineer, and towards the latter part of the year, by the appointment of General Smyth Commanded the artillery in Fort Niagara until discharged. Commanded the [27th] Regiment of Infantry. Since then appointed to the General Staff residing in New York. He would be interested in either a Civil or Military position to support his family."
Thomas Addis Emmet (pictured), another Irish immigrant, brother of Irish martyr Robert Addis Emmet and veteran of 1798, adds to Nicholas Gray's memorial to Madison on March 1st, 1815: "My long and intimate acquaintance with Col. Gray, I take the very great liberty of adding to his Memorial. That I know its content are to be strictly true. I know him to be a intelligent, faithful and meritorious Officer. With his increased debt and a family to support. I have come with the respectful reference. My conviction, that he will discharge the duties of any office he may be appointed. He will undertake with zeal, fidelity and intelligence.  " After inspection of the troops by Colonel Nicholas Gray, the Inspector General was honorably discharged from the Military service of the United States Army on December 3, 1814, with the thanks of Governor Tompkins."
On March 30, 1815, Nicholas Gray was appointed register of the land office in the Mississippi Territory. In a letter dated Nov 16, 1815, by Nicholas Gray to Brigadier General Parker from the Land Office of Washington, Mississippi: "Gray describes his friend's disturbing state of health. Lieut. Dumas of the Army Corp of Engineers - New Orleans District. Who is dangerously sick at Natchez, Ms. He has the appearance of the yellow fever but it is not that disease. Since my last letter I have succeeded in getting him to my home here in Natchez and have the pleasure to say that he has recovered."
Henry Gray was born in Ireland and his mother Ellen describes their trip to America as dangerous. She states that they had some narrow escapes with their lives. Governor Tompkins describes Henry as a fine and intelligent young man. Henry became a Midshipman on January 1st., 1812, and served on the USS Essex. In the War of 1812, the USS Essex under Captain David Porter was very successful until the Battle of Valparaiso, on March 28th, 1814.
Nicholas Gray to JM April 25, 1817: Washington, Mississippi Territory solicits promotion to lieutenant in the Navy for his son Henry Gray. Letters received by the Secretary of the Navy. Henry was promoted to Lieutenant (on) April 1, 1818. His last appearance on the records of the Navy Department showed - Lieutenant Henry Gray of Albany, New York in 1818 was reported by the United States Navy as dead and that he had left no property. Located at: "Niagara Falls [Ontario] Public Library"