The message on this letter card probably relates to the Prisoners from the German Liner Belgia, captured at the very outbreak of the First World War - 4th August 1914.
The card is dated the 8th of August 1914, the same date as is on two postcards (see link below) showing the liner in Newport.
The message says:
Dear A.
Still on duty here. We removed the German prisoners yesterday. Was guarding Lock Gates last night. Have not undressed or taken my boots off since leaving Bridgnorth. Don't forget to put F. Comp. on letters or P.C. I cannot write a letter as we cannot get at our kit bags and are not allowed out. Best love Bern