The mortar had an early form of Krupp horizontal sliding-block breech and it fired separate-loading, bagged charges and projectiles.

However, if the area was constrained by geography like a port at the mouth of a river the navigation channels could be measured ahead of time and firing ranges calculated.

The mount consisted of a rectangular steel firing platform with a pivot at the front and two wheels at the rear to give a limited amount of traverse.

The M1877 was designed with the lessons of the Franco-Prussian and Russo-Turkish war in mind where field guns with smaller shells and limited elevation had difficulty overcoming fortifications.

These consisted of twelve rectangular plates connected with elastic links and are visible in many photographs of World War I artillery from all of the combatants.

Since aircraft of the period were not yet capable of carrying large diameter bombs the burden of delivering heavy firepower fell on the artillery.

The majority of combatants scrambled to find anything that could fire a heavy shell and that meant emptying the fortresses and scouring the arms depots for guns held in reserve.

In 1916 the Germans transferred twenty M1877's to the Western Front where they were assigned to heavy artillery battalions of the army and these soldiered on in declining numbers until the end of the war.