Dear Sirs:
IIRC cluster munitions were first developed and deployed by the Germans in WWII. The first mass use of the new weapon came at the Battle of Kursk.
The problem was how to aid the German Armour in its break-through of Russian defensive anti-tank positions. Before during massed Russian tank attacks, lone German anti-tank guns were simply overwhelmed.
To meet this challenge, the German gunners grouped anti-tank guns (in German, PAK - Panzer Abwehr Kanone - anti-tank gun) together en-masse in so-called "pak-fronts", under the direction of a single fire-control center.
Tanks were engaged at maximum range by the whole set of guns and thus could be destroyed very quickly. Unfortunately the Russians quickly adopted the idea themselves and designed anti-tank defenses with pak-fronts several kilometers deep!
To break through these defenses, the Germans developed 100 kg bombs containing 100 1-kg bomblets, bursting open at a critical height and dispersing the sub-munitions, the result was to annihilate the gun crews - allowing a breakthrough the pak-front.
Incidentally the Germans also developed the fuel-air explosive (the so-called Oil-Shells, in Russian "thermobaric weapons") first used in Sebastopol as well as tank-busting aircraft - Ju 87 Stuka's with 37 mm guns in the undercarriage!
The greatest aerial tank killer was Hans-Ulrich Rudel and the commander of these aircraft was General Freiherr von Richtofen - the Red Barons nephew!
As to the Chinese, they have a complete range of cluster munitions, and FASCAM ammunition for the artillery (Family of Scatterable Mines).
Hope this helps,
Best Regards,
Dusky Lim