Fe wnaeth Cyffinwyr De Cymru faesu saith bataliwn ( tua 3,500-4,500 o ddynion) yn ystod dyddiau cynnar brwydr y Somme ar y Ffrynt Orllewinol ym mis Gorffennaf 1917. Ar yr 16eg a'r 17eg o Orffennaf, roedd y Bataliwn 1af - rhan o'r 3ydd Brigâd - yn Bazentin Le Petit Wood, ger Mametz Wood. Enillodd y bataliwn dir sylweddol, gan ddioddef man golledion yn unig - lladdwyd 4 ac anafwyd 10.

Mae'r negeseuon hyn oddi wrth Brif Swyddog Cyffredinol Brigâd Rhif 3 at Brif Swyddog Bataliwn Rhif 1 Cyffinwyr De Cymru ac maent yn darllen fel a ganlyn:

'Message timed at 0122 hrs 16th July 1916
1st Div wire reads following from 3rd Corps Commander which please convey to all ranks begins aaa well done 3rd Brigade and artillery supporting them aaa. Ends.'

'Message timed at 0122 hrs 16th July 1916
1st Div wire reads following from 3rd Corps Commander which please convey to all ranks begins aaa well done 3rd Brigade and artillery supporting them aaa. Ends.'

'Message timed at 445 hrs 17th July 1916
GOC 1st Div desires to express to all concerned in last nights operations arty [artillery] and infy [infantry] alike his appreciation of their splendid effort as the result of which the whole situation on the 3rd Corps front has been materially altered for the better aaa He feels sure that they will carry through further operations with the same precision and dash as they exhibited last night Ends.'