Hi Steve
This area of ops is sadly neglected Im sorry to say, & Ive always had trouble finding extra detail myself mate.
Ive been browsing the books I have & am afraid to say that i cant find reference to any action taking place that day at all. I believe the 'Dunsterforce' was in & around Baghdad during March (Maj-Gen Dunsterville & his gang) but even that gave no clues Im afraid. Later that month saw a battle at Khan Baghdadi (see here
http://www.1914-1918.net/mesopot.htm) but again it doesnt relate directly.
Theres a snippet here fromm the Hampshires in the area at the time
http://www.pauljerrard.com/ww1/DiaryAug200...m#_Toc522196725 but its not the Welch boys ... may relate if you look into it a bit futher praps????
Another indirect snippet about the Oxfords can be seen here
http://home.clara.net/wfha/flbbiog/ww1b.htm. That puts them at 'Uqbah' which from memory is north of Baghdad(?)
In general, the Infantry were road & rail builders & 'holders' around this time, but thats really based on the lack of firm info stating otherwise! So unless Ive missed a battle or skirmish, your Gt Uncle was likely killed on duty at an outpost or similar???
Id suggest 'Googling it' & trawling through the results Steve!! Try the Battalion he served in & maybe 'Sharqat' & 'Khan Baghdadi' & see what happens following those threads.
Sorry I cant give you anything firmer but good luck to you
Steve