Hi Caryl, i see our illustrious, untiring, fearless , devoted & most beautiful leader
of our family forum, Marion has aided you in your quest for information.
Sorry i havent had a lot of time lately for research but here is what i have.
The 311th Inf Reg was part of the 78th Inf Div. It appears from the dates you give that your grandfather transfered to the 280th ECB stateside, The 78thID shipped out to Europe Oct `44.
I dont have their full history, but the 280th Engineer Combat Battalion was a non-divisional unit of the 9th U.S. Army from 5 September 1944 - 5 May 1945.
http://www.twofortyforth.org/9thto.htm
The only copies of the History 280 Engr C Bn [280th Engineer Combat Battalion]
that is available according to a Worldcat search is 1 copy at the:
BRUCE C CLARKE LIBRARY
FT LEONARD WOOD, MO
and 1 copy at the :
US Army, Mil Hist Institute
US Army Heritage & Education Center
CARLISLE, PA
It also shows a copy at the New York Public Library, but a search of the site shows up as unavailable.
http://www.worldcat.org/title/history-280-engr-c-bn-280th-engineer-combat-battalion/oclc/16100831