Complex sentence: During World War II, Nazi Germany attempted to build several aircraft carriers, two of these were to be of the Graf Zeppelin class, Flugzeugträger A "Graf Zeppelin" and Flugzeugträger B "Peter Strasser".
Split into simpler sentences: During World War II, Nazi Germany attempted to build several aircraft carriers. Two of these were to be of the Graf Zeppelin class, Flugzeugträger A "Graf Zeppelin" and Flugzeugträger B "Peter Strasser".