During the second world was the United States Army used a tank-mounted multiple rocket launcher the Rocket Launcher T34 (Calliope).
Placed on top of an M4 Sherman tank, it could fire 4.5 inch M8 rockets from 60 launch tubes.

A Rocket Launcher being tested and demonstrated for Fifth Army officers. The Launcher is mounted on a Sherman Tank and has 54 tubes.
The Sherman was designed in 1940 and entered production the following year. The version that was the most common was armed with a 75 mm M3 L/40 gun and supported by a .50 cal Browning machine gun, accompanied with two more .30 cal machine guns, one in the turret and one in the hull.
This firepower was mainly used to support infantry attacks in combined actions. The tank’s armor was 93 mm (3.7 in), or 118 mm (4.6 in) in an improved version which utilized the 76 mm gun.
There were 3 variants of the Calliope:
Rocket Launcher T34
60 4.5 inch rockets were carried in this version, arranged in a group of 36 tubes which were carried on top, a two 12 tubes groups were carried on the bottom which could be jettisoned.
Firing 4.5 inch rockets from M4-Sherman “Calliope” multiple rocket launcher, mounted on M-4, No. A-3 tank. 14th Armored, France.
A T34 launcher mounted on top of a Sherman M4A3
Rocket launcher T34 Calliope 80th Division
Sherman With T34 Launcher advancing in Germany – 1945
Loading rockets on a camouflaged Sherman
T34 Sherman Calliope Rocket Launcher 14th Armored Division 1945. Note the sandbags attached to the sides.
Another shot of what appears to be the same Sherman
Four T34 equipped Sherman tanks, most probably in Germany 1945
Rocket Launcher T34E1
Basically the same as the T34 launcher but the groups of 12 jettisonable tubes were replaced by groups of 14 tubes.
It has proved very difficult to find pictures for this variant.
Loading rockets on a T34E1 launcher
Rocket Launcher T34E2
The caliber of the rockets was increased from 4.5 inch to 7.2 inch, the number of tubes remains at 60. It saw combat in 1944-1945.
Loading rockets on a T34E2 launcher
Rare color image of the T34E2 launcher
Soldiers of the 3rd Armored Div hanging around a Sherman Tank with a T34E2 launcher attached.
Sherman Tulips
In 1945, there were British Shermans fitted with two rails, one either side of the turret, which could carry two 60 lb headed rockets. Tanks of the 1st Coldstream Guards used them at the crossing of the Rhine. The tanks were called “Sherman Tulips”.
Rocket-armed Sherman tank of the Coldstream Guards crossing the Dortmund-Ems Canal, April 1945
Shermans equipped with 60-pound rockets, on the first Sherman, the rocket on the right has been fired.

Video
https://youtube.com/watch?v=9_uP-AmUEzA