... the 'Hound Dog' missile was an early version of a cruise missile. Two were carried under the wings of a B-52 Stratofortress, while additional 'free-fall' weapons could be carried in the B-52's bomb-bay. The missile would be launched at a distance of up to 750 miles from it's target. Relatively small and fast (mach 2) the 'Hound Dog' was much less vulnerable to Russian air defenses than it's bigger much slower mother-ship. Each missile was armed with a W-28 one and a half megaton nuclear warhead. 'Hound Dog' missiles remained in service until 1975 when they were replaced by more modern versions of the cruise missile.
In the late 1950's and early 60's, as Soviet air-defenses became more effective, the 'Hound Dog' system was developed so that bombers could execute 'stand-off' attacks on heavily defended targets. (video)