A smiling British soldier giving two thumbs up to the camera while escorting a column of German POWs after the Siege of Tobruk; ca. 1941
A British soldier gives a “two-fingered salute” to German POWs captured at the Second Battle of El Alamein, Egypt; ca. 1942
The “two-fingered salute”, is commonly performed by flicking the V upwards from wrist or elbow. The V sign, when the palm is facing toward the person giving the sign, has long been an insulting gesture in England, and later in the rest of the United Kingdom; though the use of the V sign as an insulting gesture is largely restricted to the UK, Ireland, New Zealand, and Australia. It is frequently used to signify defiance (especially to authority), contempt, or derision. The gesture is not used in the United States, and archaic in Australia and New Zealand, where the finger tends to be used in such situations instead.
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German POW captured by the Soviets after defeat in Stalingrad, 1943
It’s quite sad knowing most of the men in that photo won’t survive the captivity that awaits them.
German PoWs in American captivity forced to watch footage of concentration camps. Taken soon after the end of World War 2, location unknown.

The majority of the German POWs sent to the US were captured later in the war and did not join in the German army by choice but rather by force. They were not supportive of Hitler’s agenda and only fought in fear of what the Nazis would do to their families in retaliation. So in this case, it is likely that they were genuinely appalled by what they were seeing or did not want their picture taken.