I will answer this from the perspective of two photos which I think are famous within the Invasion of Normandy.

The first being: "Into the Jaws of Death", photographed by Robert F. Sargent. He was the chief photographer mate in the US Coast Guard. I did a lot of digging for this answer. A chief photographer mate serves as the Navys professional photographer. Here is the general info on the position from about careers: US Military.

"They operate different kinds of still and video equipment on a variety of assignments. PHs cover news events, ceremonies, accident investigations and provide photography for release to Navy and civilian publications or for use in Navy historical documents. Their work may include portrait photography, photographic copying, aerial photography for map making and reconnaissance, scanning and editing of digital video images along with the production of training films, video news reports and all other types of audiovisual work. Along with the training provided to support all aspects of photographic laboratory work, some PHs receive additional training in the troubleshooting and repair and maintenance of photographic equipment and camera repair. This is a five-year enlistment program."

Source: http://usmilitary.about.com/od/enlistedjob1/a/ph.htm

With regard to Robert F. Sargent his job was to take photos of the invasion for those specified purposes. He took professional photos as a means of documentation. This particular shot (Into the Jaws of Death) is of Company E, 16th Infantry, 1st Infantry Division landing on Omaha Beach .

Another example would be someone who is civilian and not associated with the military. Robert Capa of LIFE Magazine also captured images of Omaha Beach on June 6, 1944. On D-Day he took eleven photos from what I am reading and they selected ten of them for publication in LIFE Magazine on June 19, 1944. He says the following about his experience,

"The war correspondent has his stake — his life — in his own hands, and he can put it on this horse or that horse, or he can put it back in his pocket at the very last minute ... I am a gambler. I decided to go in with Company E in the first wave."

He risked his life on many occasions to get the shots and is quoted as saying, "If your pictures aren't good enough, you aren't close enough." Capa is an individual who got the photos that are known for being iconic today. He is just one individual who worked to capture a moment so that we may see what the action on the front line looked like. It is as close as a civilian can get to experiencing war.

I recommend this website for more on Robert Capa: http://www.skylighters.org/photos/robertcapa.html.

Picture of Capa's work: http://en.wikipedia.org/wiki/Robert_Capa#mediaviewer/File:Capa,_D-Day1.jpg

Hopefully this has helped you out and answered your question. I enjoyed answering it and doing some of my own research for it.