During which war was The Last Supper damaged by a bomb explosion?

The Last Supper was damaged by a bomb explosion during World War II.

On 16 August 1943, an Allied bomb struck the Santa Maria delle Grazie complex in Milan. The blast destroyed the refectory’s roof and damaged nearby parts of the building, leaving Leonardo’s mural exposed to the weather while reconstruction took place.

The painting survived largely because it had been protected with sandbags, mattresses, and pillows. Those precautions helped shield the wall from direct bomb splinters, although the explosion and resulting structural damage still endangered the already fragile surface.

World War II was only one episode in the mural’s long history of threats. Dampness had begun affecting it within decades of completion, and later it suffered from smoke, flooding, wartime exposure, careless restoration, and a doorway cut through the lower wall in 1652. The bombing is therefore remembered as a dramatic near-loss, not as the original cause of its deterioration.