Explosive Ordnance Disposal experts attended the scene and identified the weapon as a mortar bomb from WWII.

The safest and quickest place to dispose of small UXO items found in coastal locations is in shallow water. As such, the army team blow up the mortar on the beach, using plastic explosives.   

Click here to see a video of the detonation.

Mortar bomb wwii
A 2″ british mortar bomb used during wwii.
What was a mortar bomb doing here?

Throughout the early years of WWII, Littlehampton was a garrison town. The War Office closed the beaches to public access and set about fortifying them with obstacles and minefields.

Army units requisitioned various buildings and set about establishing gun and mortar positions. Thousands of inhabitants were evacuated to the countryside as Littlehampton became a ghost town.

Burial of ammunition caches was not uncommon in coastal locations during the war. After the threat of invasion had passed many of these remained buried and forgotten about. Consequently, present day finds, such as this mortar bomb, are not uncommon.