Baedeker to have three of his four sons − Hans, Ernst and Dietrich − beside him in the firm, as editors and writers. Karl Baedeker III, the fourth son, entered academia and rose to become a professor of physics at the University of Jena. He was killed in action at the Battle of Liège in August 1914. It was his son Karl Friedrich who revived Verlag Karl Baedeker after the Second World War. During his reign, which lasted over 50 years, Fritz produced 73 new "Baedekers", as they came to be known universally. The Baedeker travel guides became so popular that
Baedeker he published his first offering—10,000 copies of "Schleswig-Holstein". This was printed in Glückstadt near Hamburg and contained some advertising to balance the books, as did some of his other contemperaneous titles. Allen & Unwin, the London publisher, once again helped the Baedeker firm with another loan and he published more city and regional guides in the years that followed. In 1951, Karl Friedrich and Oskar Steinheil, a pre-war Baedeker editor, signed an agreement with Shell AG, the subsidiary of Royal Dutch Shell, and Kurt Mair (1902–1957), the German printer and publisher based in Stuttgart, to produce a series of motoring