My reference doesn't have a lot of information, but here is what I was able to find:
204th Engineer Combat Battalion was activated at Fort Devens, MASS.,25 Feb 43; departed NY P/E, 2 Jan 44; arrived England, 8 Jan 44; arvd France-ETO, 2 Jul 44; returned to NY P/E, 26 Oct 45; inactivated at Camp Kilmer, NJ, 27 Oct 45.
Ardennes-Alsace, 16 Dec 44 / 25 Jan 45 Central Europe, 25 Mar 45 / 11 May 45 Normandy, 6 Jun 44 / 24 Jul 44 Northern France, 25 Jul 44 / 14 Sep 44 Rhineland, 15 Sep 44 /21 Mar 45.
I don't have any casualty figures, but considering the unit's time in combat, I am sure that they were high.
Location at war's end, 15 Aug 45, Burglengenfeld, Germany.
I had hoped that I could identify the ships involved in his crossings, but my lists are not as complete as one would hope. Sorry.
That is about all I can tell you of your dad's military history.
Please feel free to contact me if needed.
With best regards,
Louie Franklin Turner.
World War II Order of Battle, Shelby L. Stanton, author, Galahad Books, NYNY, publisher. 1991.