Excluding rockets, the Russian 240 mm Mortar M240 — both the 2S4 vehicle and towed M240 systems — is the largest caliber land-based artillery weapon in use. Part one of the following article will cover the basic characteristics and its employment in the Yom Kippur War by the Egyptian and Syrian armies, as well in Afghanistan by the Soviets and during the Second Chechen War by the Russian Army. The second part (published in a few days) will cover its use in Ukraine and Syria.