The SOMUA S42 was a French Army replacement tank for the SOMUA S35. It was roughly par with the German Panzer IV with thicker, better sloped armor, a 75mm high velocity main gun that was almost the equal of that of the IV and a stronger engine to move the heavier weight at an acceptable speed. In addition, it had a five man crew with a gunner and loader to handle the main gun freeing the tank commander to better manage its operation.
Lt. Aristide Demange was pleased to have a pair of S42s assigned to assist his company to advance from Rance. However, while the new char stood a good chance against Panzer IVs, the advance was stopped cold by a Tiger. The first Demange was aware of it was when one S42 suddenly brewed up. The second got off a shot and hit the Tiger but the round bounced off without harming it. The Tiger then destroyed the second S42 and began shelling the advancing infantry with HE. Demange realized further advance was hopeless and ordered his company to dig in.
This model of tank is an invention by Harry Turtledove to reflect French improvement in its tanks as the alternate WWII progressed. In OTL the French recognized the shortcomings of the S35 shortly after it came into service. It began a research effort designated the SOMUA S40 / Char G1 which would have thicker armor and a 75mm main gun. With the outbreak of World War II and the fall of France, this project did not progress beyond the drawing board.