It was stated that 1911 the Colonial War Muster Rolls were burned during a fire at the State Library. Do you have anymore information on your ancestor? The French and Indian Wars last a few years so there is quite a time span.
You will find John Kent listed in the book about the New York Colonial Muster Rolls. Many libraries have copies of these looked for online versions and many are very limited due to copy right infringements. But did find an index showing him listed with a Peter Kent as well.
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Found the French and Indian War Muster Roll with 13 soldiers named John Kent but some of them were captured. Go to familysearch.org, it is a free website you just need to register to see this https://www.familysearch.org/ark:/61903/3:1:3Q9M-CSB5-PW9P-M?cat=1471369
Dear Mr. Kent,
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Any surviving records of pre-Revolutionary War service in colonial militias may be in the state archives of the colony in whose militia he served. Several different colonies contributed to the defense of Fort William Henry. The nature and availability of colonial military service records varies greatly from state to state. If he served in a British Army unit, to include British units raised in the colonies such as the 62nd (Royal American) Regiment, there may be a record of him at the National Archives of the United Kingdom. The National Archives of the UK also may have other records concerning British subjects taken prisoner during the war. Also, the Library and Archives Canada and the French National Archives may be able to advise on whether any French records records of enemy prisoners of war have survived, and if so, where they are located
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