Interesting info, but some of it doesn't make too much sense.
As Alphonse was born during the Civil War, his father would have been pretty old if he had fought in the Battle of Chateauguay (1813) during the War of 1812. This would have made him almost 60 when Alphonse was born. Not implausible, but definitely curious.
The red uniform is also curious, as the US Army issued a deep blue wool uniform with white or gray pants for most of its history.But the red uniform could well have been British.If memory serves me, the Chateauguay Historical Commission has a list of the men who fought in the battle. Might be very valuable for you.There are also a couple of excellent military historians whose names I can send you.They may be able to search the military archives for you (usually without a fee, if it's an easy search).
Otherwise, your best bet is to approach the parishes in/near Huntingdon to see if you can find the baptismal records for Alphonse.
Happy hunting.Let us know if you figure out the puzzle!