Complex sentence: Following his return, captain Paul König wrote a book (or possibly had it ghost-written) about the journeys of the "Deutschland", which was heavily publicised, and intended to sway both US and German opinions.
Split into simpler sentences: Following his return, captain Paul König wrote a book (or possibly had it ghost-written) about the journeys of the "Deutschland". The book was heavily publicised, and intended to sway both US and German opinions.