I didn't know that Germany's national anthem was actually the second movement of Haydn's String Quartet No. 62 in C maj (Op. 76 No. 3), more commonly known as the Emperor Quartet, until I chanced upon the anthem in YouTube today. Such an alluring and beautiful melody!
A little more background on the music. Haydn created the melody for the text Gott erhalte Franz den Kaiser (God Preserve Emperor Franz) in honour of the reigning Austrian Emperor Franz II. It was first sung in theaters throughout the Austrian realm on the Emperor's birthday, 12 February 1797. Following its popularity, Haydn used it as the material for the second movement of his string quartet. The Emperor's Hymn was the last music Haydn played before he died on 31 May 1809.
It formed the melody of a Protestant hymn and in 1853, became the national anthem of Austria! The tune was given up after Austria's defeat in World War II and was subsequently taken up by Germany in 1950!
Guess they couldn't help it, with such an irresistible melody by beloved Haydn!