For the Allies as well as the Germans, it will be the longest day.
The events of D-Day, told on a grand scale from both the Allied and German points of view. 
The retelling of June 6, 1944, from the perspectives of the Germans, US, British, Canadians, and the Free French gets an all star production. One of the great war movie epics, it has all the requisite blunderbuss spectacle and heroism as the Allies invade Normandy. It's not hard to see why it was such a box office winner, sure it's a touch too long given that a lot of characters don't really have much to do, but performances are strong and the slices of humour off set some of the national stereotypes on show.
One has to marvel at the ambition of the production, Fox Studios boss Darryl F. Zanuck spent $10 million to get it onto the big screen, and it shows. Narrative is split into three parts, the preparation, the operations on land and sea in readiness for the Normandy assault, and then the landings in all their powerful glory. For sure we have seen more authentic war movies post The Longest Day, but it undeniably deserves its place as a template movie whose power to entertain in any era forever holds firm. 8/10