Ok, how about this, in order to fire a cannon you have to win 100 random fights to unlock the ability to fire the Mortar, and it gets the same war kills as normal.
300 random fight wins unlocks the Heavy Turret.
700 random fight wins unlocks the Artillery Barrage.
1,000 random fight wins unlocks the Goliath Cannon.
1,600 random fight wins unlocks the use of the Satellite Destroyer.
NPC wins will not count towards unlocking the faction weapons.
after you achieve 1,600 random fight wins and unlock them all, you can fire each one once. after that,
10 wins to use the Mortar once more.
30 wins to use the Heavy Turret once more.
70 wins to use the Artillery Barrage once more.
100 wins to use the Goliath Cannon once more.
160 wins to use the Satellite Cannon once more.
Again, NPC wins will not count towards the quota of wins.