Answer: Walter Cronkite
Walter Cronkite (1916 - 2009) was the one who accompanied the US Army, as a reporter for the United Press Agency, during the invasion of Normandy on June 6th, 1944, during the Second World War (unlike Hemingway, who although he was in Normandy too, he was not authorized to disembark and had to observe the outcome of the battle with his binoculars from a pontoon).
It should be noted that Cronkite also overflew Germany in aerial bombardments and was a reporter during the Nuremberg trials.