Decisive advances in nuclear research at the end of the war led to several ideas for tactical applications. Among them, the reliable 155mm 'Long Tom' gun test-fired the experimental W48 shell with nuclear warhead, allowing it to annihilate any target on a limited scale. These shells, fired from very long range, are far more effective than any other artillery gun. Those tests made on the Long Tom led to the development of the first 280mm nuclear howitzer, nicknamed 'Atomic Annie'.
Nuclear Long Toms are precious units to gain, as they fire only one powerful shot with each attack, and appear in the game when the campaign grants you one. With over eighty-thousand damage to ground-based enemy objects, the Nuclear Long Tom is a guaranteed kill against any enemy unit. However, keep in mind as commander that a nuclear explosion will occur if destroyed by enemy forces head-on. Thus, the user should protect it at all costs.
Even with their massive radius, range of fire and damage, the Nuclear Long Tom takes too much time to reload and you must choose targets individually, that means, they don't fire automatically, as normal artillery does, you must choose always what targets they must attack.
Nuclear Long Toms are buildable in the new “Nuclear war” mode that will be included in the Manhattan Project Expansion Pack, which was released in December 2010 on Xbox Live®, PlayStation Network® and Steam®, for free.
The American government really did experimented with tactical uses for nuclear weapons, one of which really was a 155mm, 6-inch long, 118 or 128-pound artillery shell, code-named W48. It was reported to have had an explosive yield equivalent to 72 tons of TNT (0.072 kilotons) which (when compared against other nuclear weapons such as Fat Man, Little Boy, Castle Bravo, etc.) was actually rather small. However, W48 was not manufactured until 1963, and all models of W48 have been retired since 1992.
Likewise, 'Atomic Annie' really did exist: it's official designation was the 'M65 Atomic Cannon'. However, it wasn't developed until the early 1950's, after World War II officially ended, but was fielded in 1953; primarily in the European and Korean theaters.
The Soviets, once they got the technologies, went the other way. The earliest design was a 406 gun on a tank chassis. The second shot would usually destroy the vehicle. The munition as well was never delivered. Instead, efforts were put into miniaturizing devices to existing calibers, rather than building guns to accommodate them, - to 203mm, and then, finally, the common 152,4mm. Every Russian field howitzer can go nuclear in a second. Beware.
Nuclear Long Tom shells have a blast radius, which can hit several units simultaneously. The single shot from this unit is best employed when fired on a tightly-knit groups of enemy forces which destroys all of them.
The blast from a Nuclear artillery shell can, and will, destroy friendly units. Use caution when deploying a nuclear artillery strike.
Buildings are sitting ducks. If the NLT is aimed at a building, it always manages to destroy it, regardless of whether it actually hits the building.
During the DLC 'Operation Zapad', the AI will field one of these, making it impossible to move ground troops across the river. The best way to destroy it is with air power.
Never deploy all your Nuclear Long Toms together, if the enemy manages to destroy one of them the nuclear explosion will result in a chain reaction destroying all your other Nuclear Long Toms (and most other units) nearby. This also applies to the Atomic Center so never EVER build it next to your headquarters, if the Atomic Center is destroyed you can find yourself without RUSE's and without a command building (if you haven't deployed a secondary HQ).
Because the Nuclear Long Tom is always most vulnerable from the air, having a very strong anti-air defense is key to keeping it safe from enemy air forces.