I think the film title is "Machineguns versus Tanks" but there are no tanks. Lots of different guns, though.
Mitrailleuse contre tank
The field gun is a Canon de 155 L Mle 1918 Schneider - a 155mm Mle 1877 de Bange barrel on the carriage of a Schneider 155mm howitzer.
Only a few were delivered before the end of WW1 and the remainder of the 120 gun order in 1919 and 1920.
Charlie
