Ah, Thomsen. When I see the beginning of the movie I always wonder whether the actor actually acted (he is an alcoholic) or really was wasted.
Perfect analysis. Only one of the officers, the young, stiff, well-groomed XO, is a nazi. When he repeats party propaganda about the Brits being weak the skipper makes fun of him via calling him Hitlerjugendführer and telling him to play "It's a long way to Tipperary".
Yes, the Tommies are their enemy but they are not too eager to hear the name of Dönitz, the CiC of the navy, because they feel on the one hand like cannon fodder and on the other hand they want more resources. It's precisely this tension between being professional soldiers and human beings who want the war to end, a tension which the audience shares, that makes the movie interesting. You empathize with the characters and are fascinated by the technical side of the sub and the ability of the captain lieutenant to calculate ship movements in his head yet you are also terrified by the conditions they live in and the crimes they commit.
While the seasoned seamen are war weary as they know what awaits them out there the movie does not sacrifice the eagerness of everybody on the sub to release their torpedoes after having been out there for weeks while doing nothing for the sake of delivering a message. And precisely via being nothing else than a movie based upon a novel based upon Buchheim's experiences, via being as realistic as possible, it becomes probably one of the best antiwar movies. So Truffaut has been wrong, you can make an antiwar movie simply by showing war as it is.
Das Boot is perhaps comparable to Platoon which is more fictional (the difference with Das Boot is that Platoon focuses on the crimes of individual soldiers whereas Das Boot views war as systemic problem and soldiers as nothing but pawns in this game) but at least in the beginning it is also simply based upon Stone's experiences as an ordinary soldier and thus lacks the artificiality of many other war movies.