I don't have any information about this photo other than it's either my Uncle or my Grandfather, both named Robert Black of Glasgow, Scotland. If it's my Grandfather it's WWI, and if it's my uncle it's WWII. Can anyone ID by the uniform?

Robert Black, Scotland

My dad w/fellow soldiers from the 28th Infantry. Pennsylvania.. Keystone Division. In training in Fort Indiantown Gap PA or Europe before invasion. My dad is on the right... Francis George Orzechowski.. Normandy thru Bulge.. Master Sergeant  US Army

My Dad W/ fellow soldiers

Les Siviter, (Front row far right) was part of 131 Field Ambulance, left behind at by the BEF to tend the wounded, captured and marched through France and eventually entrained first to Stalag 20A and then transferred to 20B in Poland. From here he was sent to Faulen to work on a state farm for the next four years and was repatriated with other non-combatants in October 1943. Les will be 90 in October this year and amazingly still opens his gentleman’s hairdressing shop most days of the week and most weeks of the year.