I can't find a history documentary, can you help me?

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Yesterday I had History class and teacher showed us one episode from a documentary about WWI [ I think in the next episodes will be the second world war too, but I'm not sure]. The problem is that the teacher began to explain something from 5 to 5 minutes, without stopping the movie, so we had to listen to teacher and the narrator(/to read the subtittels] of the movie in the same time xD, so I couldn't understand the episdode very well. I want to rewatch the episode and to watch the other episodes too, in advance, to be prepared for the class, but I can't find the movie, because the teacher didn't told us the name of the documentary. All I know is that it was uploaded on you tube , it had many episodes [10/15/not sure] andthe scenes from the movie were real, it were filmed directly from the battlefield, from that time. If anyone from here knows the documentary I'm talking about, please give me the link. Thanks in advance! Have a good day!