The Mortier de 270 mm modèle 1885 was a French heavy mortar employed as siege artillery during the First World War.

The later Mortier de 270 mm modèle 1889 was based on the mle 1885 and adapted to the coastal artillery role by fitting the same barrel to a different carriage.

[1] The recoil system for the mle 1885 consisted of a U-shaped gun cradle which held the trunnioned barrel and a slightly inclined firing platform with hydraulic buffers.

The mortars could also be transferred to 600 mm (1 ft 11+5⁄8 in) narrow gauge rail wagons for the final leg to their firing positions.

Site preparation included creating a base of wooden beams then assembling the mortar with cranes and block & tackle.