My father was also in the 599th AAA AW Bn as Battalion Surgeon's Assistant. I have had problems finding anything about that unit as well. I do have the following locations of the 599th from his army records: 12/10/44 to 12/16/44 enroute to UK. A search of the troop ships shows that it would have been the Queen Mary that left NY and arrived in Gourock, Scotland on those dates. In UK until 3/2/45, then France 3/3/45 - 3/9/45, Luxembourg 3/9/45-3/13/45, Germany 3/13/45-11/23/45 (although with the 599th only until 9/25/45). Records indicated ribbons for Rhineland and Central Europe.
I have a newpaper article that has a story that my mom clipped titled The Patton Rampage and describes forces crossing the Rhine as 3rd Army, 4th Armored Division.
Was the 599th AAA AW part of the 4th Armored Division? I can't find anything that tells me the part between 3rd Army and the 599th AAA AW.