Yes, so far the only one used was in wwII.
The only nuclear weapons ever used in warfare were the Little Boy and the Fat Man, used by the USA against Japan in World War II.
Missiles with nuclear warheads have never been used in war. The only nuclear weapons ever used in war were the 2 used to end WW2 in Japan. These were gravity bombs.
The ONLY nuclear device(s) ever used in a world war was the Hiroshima & Nagasaki atomic bombs that were dropped in August of 1945, ending WWII. Nuclear powered naval ships were used in a number of other conflicts, but not nuclear weapons.
Just WW2, they have never since been used in war.
Only in World War Two and only two were ever dropped (both on Japan) Then we got the cold war and the whole mutually assured destruction so no one else has done anything besides test and stockpile nuclear weapons.
Fight wars without the use of nuclear weapons; limited wars.
That in the atomic age (atomic weapons) only limited wars can be fought. Nuclear weapons would mean total war.
Presidents (Commander in Chiefs) now knew they could NO LONGER declare TOTAL WARS; in the age of nuclear weapons, wars had to be fought as LIMITED WARS...limited to "non-nuclear weapons." Such as Korea & Vietnam...to stem the tide of communism.
The Atomic Age created the cold war. With nuclear weapons, total wars (such as WW2) could no longer be fought. Only limited wars such as the Korean War and Vietnam Wars could be fought. Limited to only CONVENTIONAL weapons (Non-nuclear).
Plenty of weapons were used, but no world war occurred nor were nuclear weapons used in any of the wars that occurred. The cold war was a very strange political and propagandawar between the US & USSR, that included no direct military conflict between them.
The advent (arrival) of nuclear weapons in 1945 (Hiroshima & Nagasaki) negated (nullified or invalidated) declared total wars. No longer could wars be fought with ALL available weapons (e.g. atomic bombs) without the risk of "mutually assured destruction." Consequently, only wars "Limited" to the use of conventional (non-atomic) weapons would or could be used.
Nuclear weapons only serve as a deterrent to war when both warring nations possess them. If only one nation has them or neither do, a conventional war is still very possible. That is why all of the Cold War wars occurred in third world countries where nuclear weapons were not present. In contrast, the Cuban Missile Crisis (and the corresponding Turkish Missile Issue) did not lead to war between the USA and the USSR specifically because both nations had nuclear weapons which could effectively serve as a deterrent to the other.