During the Cold War, both the United States and the Soviet Union had nuclear artillery shells for 155mm and 152mm howitzers, respectively -- those would have a yield of about 100 tons on the low end, up to 2 kilotons on the high end. Higher-caliber artillery pieces, like a 203mm piece, could have a shell on the order of 10 to 15 kilotons, roughly approaching the Hiroshima bomb's power.
The American W82 155mm nuclear artillery shell[0] weighed 43kg (95lb), was 860 mm (34 in) long, and had a yield of 2 kilotons -- equivalent to 500 full WW2 heavy bomber loads.
These shells (as well as bombs and warheads with similar yields, carried by planes and missiles, respectively) are called tactical nuclear weapons -- meant for use on the battlefield, to break up enemy formations. Their blast radius is relatively small. It was theorized that if the Cold War went hot and a conventional WW3 broke out, if the Soviet Union was pushing NATO forces back, then the Americans would authorize the use of tactical nuclear warheads. This would likely cause a spiral of escalation, up to a strategic nuclear exchange.
The American W82 155mm nuclear artillery shell[0] weighed 43kg (95lb), was 860 mm (34 in) long, and had a yield of 2 kilotons -- equivalent to 500 full WW2 heavy bomber loads.
These shells (as well as bombs and warheads with similar yields, carried by planes and missiles, respectively) are called tactical nuclear weapons -- meant for use on the battlefield, to break up enemy formations. Their blast radius is relatively small. It was theorized that if the Cold War went hot and a conventional WW3 broke out, if the Soviet Union was pushing NATO forces back, then the Americans would authorize the use of tactical nuclear warheads. This would likely cause a spiral of escalation, up to a strategic nuclear exchange.
[0]: https://en.wikipedia.org/wiki/W82