Mouse Holing at Ortona

The Second World War Allied campaign in Italy is often called “an Engineer’s War” because of the terrain and obstacles the enemy created that had to be overcome. In December 1943, the German Army had retreated to the "Bernhard Line" across the narrowest part of the Italian Peninsula to halt or at least slow the Allied advance. The line crossed over mountain rivers swollen with winter rains that German military engineers reinforced by demolishing most of the bridges in the area to the south. They also cratered roads in defiles, torn up railway tracks and planted minefields in the craters, verges and open spaces. Furthermore, defended towns and villages were reinforced with even more demolitions and the use of mines and booby-traps.

At this stage in the Italian Campaign, the engineer resources of the 1 st Canadian Division were already fully committed to restoring and maintaining the routes forward by building bridges, clearing minefields and booby-traps, filling craters, bypassing obstacles along with a myriad of other tasks to allow the forward movement of the tanks and heavy transport vehicles.

On 21 December 1943, the Loyal Edmonton Regiment and the Seaforth Highlanders of Canada, supported by the tanks of the Three Rivers Regiment, entered the seaside town of Ortona, the eastern anchor of the Bernhard Line. Here they encountered what has been called the most intensive street fighting in the history of warfare to that time. The Engineers and Infantry Assault Pioneers were heavily involved in clearing obstacles that were restricting the advance but much of the battle now involved intense house-to-house fighting with a determined enemy.

Fighting from building to building was a time-consuming and dangerous task. Canadian soldiers were exposed to the dangerous close-in fights in the buildings and enemy fire from streets and rooftops when they exited a cleared building to move to the next.

To overcome the problems, Canadian troops employed a technique called "mouse-holing" or creating a mouse hole to connect one building to the other. In concept, a mouse hole was prepared in the common wall between adjacent houses to gain entry to the house next door. The engineers helped the infantry move forward from house to house by breaching connecting walls with hand tools or explosives. If the enemy occupied the upper floors a large demolition charge was placed n the centre of the room collapsing the house. Sheltered from enemy fire and observation, the enemy was soon driven out of the city. On 27 December the German Army broke off contact and the Battle of Ortona was won – with some particular credit to the technique of ‘mouse-holing’.

The technique and tactic proved successful and were soon adopted by other Allied armies.