The 500 pound World War Two device was picked up during dredging work.
Portsmouth Plans D-Day Commemorations
The "horror film'' events of the D-Day landings are to be commemorated on the 70th anniversary in Portsmouth with a Red Arrows display and a gathering of veterans to honour those who took part in the key Second World War battle.
The naval city is to be a central part of the UK's events to remember the sacrifices and bravery of the servicemen, many thousands of whom embarked at the Hampshire port to take part in the intrepid landings.
Frank Rosier, secretary of the Portsmouth branch of the Normandy Veterans Association, helped announce the series of events being held in June.
The 88-year-old served as an infantryman in 2nd Battalion, Gloucestershire Regiment, and landed in the second wave on Gold Beach on D-Day.
His unit was tasked with taking Bayeux on June 7 1944. He served in the intensive infantry fighting during the Battle of Normandy, and after nearly three months he was wounded near Le Havre.
Mr Rosier, who was born in Chelsea, London, but who now lives in Waterlooville, was later awarded the Legion d'Honneur by the French government for his work with the Normandy Veterans Association (NVA).
He said: "I was an 18-year-old boy who survived the blitz, had never seen a dead body, and arrived in the second wave and the carnage on that beach brought me to a halt. It was a horror film, I can't begin to describe it.
"We must never, ever forget those boys who laid dead on those beaches, the Army, the Air Force and the navy boys.
"Pure and simple, they fought for something us Brits get a bit blase about; it's called freedom.
"Portsmouth was at the centre of that operation and it's right that we hold these 70th anniversary commemorations here.''
Able Seaman Sarah George, originally from Liverpool but living in Gosport, is a member of the crew of Type 23 frigate HMS Richmond which is one of the ships which will be travelling to Normandy for the commemorations in France.
The 22-year-old said of meeting the D-Day veterans: "It all makes it real about what happened, it's quite a proud moment.
"It will be an emotional moment for the veterans as it will bring back so many memories, it's going to be a sad day for them as well.''
A veterans' village is to be set up on Southsea Common for the week of the commemorations allowing former comrades to gather and exchange memories.
On June 5, a drumhead ceremony involving veterans and the Royal Marines Band Portsmouth will be held followed by an amphibious landing demonstration by the Royal Marines and climaxing in a 20-minute aerobatic display by the Red Arrows.
On the anniversary itself, a remembrance service will be held at the D-Day stone in Southsea followed by a military parade and a live screening of the events in Normandy.
A weekend of events giving visitors a chance to experience what life was like in wartime Britain will then be held on the common.
Lee Hunt, Portsmouth City Council's cabinet member for culture, said: "Portsmouth and surrounding areas were transformed leading up to D-Day, the seafront was declared a restricted zone and thousands of international and British troops came into the city.
"We want to honour the actions of all men and women involved and it's important surviving veterans and those who played vital roles in the operation take centre stage.
"This is why it's so important Normandy veterans and their families contact us so we make sure they're invited as guests of honour to all events.''
640 men were killed when the South African troop carrier was hit by a cargo ship in 1917.
The 79-year-old man suffered a serious head injury in the Cranmer Road car park in Winton.
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