When people think of The Beatles, they rightfully think of England. However, the Beatles really owe a lot of their popularity and start to Germany, specifically Hamburg. The group traveled to Hamburg in 1960 when they had 5 members: George Harrison, Paul McCartney, John Lennon, Pete Best (the original drummer who the group found right before their trip to Germany), and Stuart Sutcliffe (who dropped out of the band in 1961 to finish his studies and sadly died shortly after he left the band). They played at a handful of nightclubs and were gaining popularity until Harrison was deported for being underage and McCartney and Best were deported for attempted arson (I can't make this up).
Later, the group returned to Hamburg. In 1961, they made their first professional recording there. They continued visiting Hamburg and playing in nightclubs there through 1962. It's said that this not only helped to build their fan base (Germany loved them), but they also got some of their signature style, namely their haircuts, there.
They returned to Germany after they hit it big and were worldwide stars. The group made a number of recordings in German - of German songs and of their own songs translated into German.
Here's "Sie Liebt Dich":
Can you figure out what song that is in English?
It's "She Loves you (yeah, yeah, yeah)". Some minor typos by whoever made the video and pronunciation isn't perfect, but it's quite good considering they didn't speak German! There're some live videos too worth taking a look at.
How about that? The Beatles are far from the only musicians in that era who recorded songs in German. Many groups and singers did so in order to build their popularity in Europe. There's many other weeks for all of those though!