(with help from A. No-Man)
If you had to bring back just one weapon, why not the M203 (M-16 with a 40 mm grenade launcher)?
You have the .223 which with you may render hors de' combat to your foeman. With the 40 mm you can literallly "blow back" any charge of Tarleton and his Green Dragoons (green meanies). The High Explosive allows you can take out artillery crews, large troop concentrations, shell the parapet of any fortified area and in narrow waters, you can challenge the Royal Navy. With a 1:7" twist bbl and the SS109, you can do 600 yard shots - something the old Longrifle would be hard pressed to do (but could in the hands of an Olympic quality shooter - pick up the Nov. '03 edition of the National Muzzle Loading Rifle Association magazine, Muzzle Blasts if you would to read a very short article on it).
If you could bring back artillery, why a 120 mm mortar instead of a 105 mm recoiless rifle?
Well, the 105 works great against troop concentrations, cavalry charges, opening town doors. However, it doesn't have indirect fire capability. Someone behind a thick dirt parapet is relatively safe until you've poured enough rounds through to penetrate. A well placed 120 mm mortar round doesn't have that problem. Bloop & boom! As for city doors and barricades (chevaux de frise), you've got the M203.
How does one transport it? A nuclear power submarine. No need to refuel, right? Don't need ICBMs on it so now you have a huge weapons bay or magazine. Being able to "pop" up anywhere along the coast, wipe out a garrison (OK, take them prisoners, disarm and parole them according to the practice of the time) and then vanish without a trace (no sonar or satellite tracking of subs) will bewilder and frighten the enemy. OK, the sub should have some weapons. Tube launched tomahawk to take out fortresses.
BTW, why stop at independence? Overthrow George III and introduce an English Second Amendment addedum to the Magna Carta.
BTW II: Gang, please don't start a thread on
"Help us win the Civil War." It was American against American and in that sense, no side won. Thankfully the 1880-1930s was a period of reconciliation and it was one country that whupped (the poor) Spaniards and then the Germans (twice).