Through a little research here is what I've pieced together. Although it is not 100% confirmable I think it takes little effort to piece this together.
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First I would like to note that everywhere you read it says Ratzinger's time as a Nazi was "brief". The same story will relate that he joined shortly after it was made compulsory in 1941 and that he fled in 1945. (or 1944 depending on what site you read).
The significant errors here is that Hitler Youth membership was mandatory starting in 1938, not 1941 as the story claims. This can be confirmed with any simple historical search.
http://www.answers.com/topic/hitler-youthAlso interestingly enough they really love to say his time in the Hitler Youth was "brief" But does 1941 to 1944 or 1945 seem brief? The war was only from 1939 to 1945 after all. He was involved in 4/6ths of it. Longer than the average tour of duty for an American WWII soldier. Hardly seems brief.
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It is known that in 1943 and 1944 Ratzinger was a Hitler Youth and was stationed protecting a BMW plant that used Dachau prisoners.
This is widely reported and can be found at numerous news websites
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The BMW plant is called Allach. Below I included information regarding it.
Allach BMW / MAN Factory In 1936, under pressure from the Reich Aircraft Ministry, BMW built a camouflaged plant in Allach, on the north edge of Allach. Initially, the Reichs Works, as Popp called them, were used to test BMW 132 engines which were brought to and from Milbertshofen (Munich) on low loaders. By 1944 there were as many as 20,000 workers at Allach, including 3000 POWs and up to 5000 concentration camp inmates, many from nearby Dachau, producing 14 cylinder, 2000 HP radial aircraft engines (BMW 801's) throughout WW II. BMW's attempt at jet engine design was less than successful as most German jets were powered by Junkers Jumo turbines.
http://bmwhistory.tripod.com/********
So according to Mapquest Allach and the location of the Dachau concentration camp is unbelievably close to one another. We're talking a few miles.
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So what was Dachau camp like? Answer.com relates that it housed more than 200,000 prisoners! 200,000. The troops that liberated said that the stench was so strong you could smell it from right outside Munich.
A quote from Answers.com
After the camp was surrendered to Allied forces, the troops were so horrified by conditions at the camp that they summarily shot all of the camp guards.
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During this same era, while Ratzinger was defending a concentration camp, Pope Pius XII was trying to save Jews by granting more than 1,500,000 jews Vatican citizenships. Also he encouraged the underground rescue of jews by Priests and Nuns. Such an advocate for saving Jews that Hitler ordered the Pope be kidnapped.
http://encyclopedia.learnthis.info/p/po/pope_pius_xii.html#World%20War%20II*********
Stories abound which say there was no choice for these people. They had to be Hitler youths. But interesting enough his neighbors while growing up did resist and actually had children that joined resistance groups. Families actually hid resistance fighters. Even their next door neighbor.
http://www.timesonline.co.uk/article/0,,2089-1572667,00.html*********
I find this all very interesting. If you read any of the newspaper articles you'll see the quoting of incorrect facts (when the Hitler Youth made membership mandatory) comes from Ratzinger's Biographer. Likewise is the claim that being involved with the hitler youth from 1941 to 1944/45 is "brief" Obviously all a SPIN to make his time as a Nazi look less threatening.
No matter what you think, you can clearly see that this is a case of media damage control.. which shouldn't be necessary when the holy spirit is supposed to select the Pope. Unfortunately I don't believe the Holy Spirit did in this case.
-A somewhat praticing 30 year old Catholic.