D-Day landings 70th anniversary: 20 facts about 'Operation Overlord'

Royal Marine Commandos moving off the Normandy Beaches during the advance inland from "Sword" beach on 6 June 1944

Friday marks the 70th anniversary of the D-Day landings - the largest airborne and amphibious assault in military history.

The pivotal move during the Second World War saw 156,000 Allied troops launch an offensive across land, sea, and air to reclaim France and the rest of occupied Europe from the grip of Nazi Germany.

The invasion was extremely risky, as proven by the disastrous Allied landings at Gallipoli 29 years earlier in the First World War, and marked the start of a gruelling 80-day campaign.

At midnight on D-Day, ground troops landed across five beaches – code-named Utah, Omaha, Gold, Juno and Sword.

By the end of the day, the Allies had established themselves on shore and could begin the advance into France.

This week, world leaders from 17 nations, as well as elderly veterans, will gather in northern France to mark the 70 anniversary of the start of the operation code-named 'Overlord'.

Commemorations will include a ceremony at Sword Beach, one of the five Allied landing beaches across a 50-mile stretch of Normandy coastline, where the Queen will be in attendance.

Here are twenty facts you need to know about the historic mission: