Keep in mind that English and German are quite close in language families (They are both Germanic base languages. English took in a lot of French Loan Words following William the Conqueror's conquering, and then the Americans took it and messed it up... or improved it. Depends on your side of the Pond.).
The thing that makes German difficult for English Speakers is that in German, nouns have gender, and there is no rhyme or reason. For example, the German words for "The Man", "The Woman", and "The Boy", all correspond to the gender you would expect (Der Mann, Die Frau/Fraulin, Der Junge) but the German word for Girl is gender neutral (Das Mädchen) (And while we're at it, double nouns in German make the long vowel sound of the second letter, not the first letter. Die in German is rhymes with Me, not My as it would in English). This shouldn't be a concern on English Translation, but it is probably the biggest difference in the two languages. Mark Twain found it so frustrating when he was learning, he once gave a speech in German noting that in German, the word for a Fish Wife (a wife of a Fisherman) is neutral, the word for a Fish Scale was Feminine, and the word for a Fish was a man, and then proceeding to tell a brief story involving a fishwife de-scaling a fish, but always called the fishwife "it", the fish scale, "she", and the fish "He".
Probably one of the most interesting things of the wars was that both Germans and English-speakers uncovered spies by asking the suspected spy a rapid fire series of questions. The questions were designed to ellicite the right answer, but to the wrong question. This was due to the German and English Question words being rather difficult to translate on the spot: The English Question words (Who, What, Where, When, Why, and How) sound like the German Question words... but don't correspond to the same question word in translation (Wer, Was, Wo, Wann, Warum, Wie). Spy hunters on both sides would ask a rapid fire series of who, where, and when (and possibly other questions just to add further confusion). If you ask Who? in English and get back a confusing "Berlin", you probably got a spy who thought you asked for a location, not a name.
Other fun pronunciation goods for German. The letter "W" is pronounced like the letter "V", letters with Umlauts (the two dots above the letter... as seen in the German word for Girl above) are pronounced with a long vowel sound. When Typewriters were a thing, Umlauts were not found on most keyboards used so it was typical to see the "Das Mädchen" rendered as "Das Maechen". Modern computers do have a keyboard command for each vowel and came back into wide use with the rise of the PC. Similarly, the Eszett (ß) is a double "S" sound and it's acceptable to use "ss" or "ß" for occurrences of a double "S" in words (Modern Swiss German does not have the Eszett, where Modern German does). German words are pronounced as spelled, so there will never be a silent letter. As I discussed, English and German are grammatically very similar in sentence structure (Subject Noun, Verb, Predicate). German has both a formal and informal second person singular (Sie, and Du) respectively, where as English does not. "Sie" is also the second person plural. A weak English speaking solider might refer to an officer of superior rank as "Sie" due to not having an equivalent in English. Finally, because English doesn't assign gender to something that doesn't have a gender, the article "The" might be pronounce like "Die" for all English words. The article "A" is "Ein, or Eine if definitely female (This is where the famous alleged Kennedy Gaff "I am a Jelly Donut" came from. Ein Berliner is one who is from Berlin where as Eine Berliner is to (non-Berliner's) a Jelly Donut like pastry (Berliner's call this a Pfannkuken, where as the rest Germany call them Berliners). This was due to some bad grammar books saying it was acceptable to leave out the article if you are one who is from a place or of a profession (this is not true) or that Kennedy's Bostan Accented German caused the people watching on TV to hear it as Eine. It's largely an Urban myth but the intent of the speech and the possibility of a man revered to such a degree as Kennedy declaring triumphantly that he is a Jelly Donut, is rather amusing and caused the legend to live.