1937 Böll finishes the Gymnasium and passes his Abitur examinations (school-leaving certificate). He begins an apprenticeship with the bookseller Math. Lemperz in Bonn, but leaves without finishing it.
Between 1939 and 1945 Böll is stationed:
- at a training camp in Osnabrück (August 39 - May 1940)
-in Poland (May and June 1940); in France (June - September 1940)
- in Germany (September 1940 - May 1942)
- in France (May 1942 - October 1943)
- in Russia, the Crimea, Odessa (October 1943 - February 1944)
- at various places on German territory from March 1944 until April 1945, when he is taken prisoner.
Böll temporarily deserts and goes into hiding with his wife in Much, not far from Cologne, but on the other side of the Rhine. Fearing he could be executed as a deserter, he rejoins the army at the end of February 1945.
Almost every day, he writes a letter to his family and to his fiancée Annemarie Cech, whom he marries in 1942.
During the war at least 20,000 people die in a total of 262 air-raids on Cologne. Almost half of its nearly 70,000 pre-war buildings are between 60% to 100% destroyed. Of its pre-war population of 770,000, only about 20,000 are still living in the city at the beginning of April 1945. On the 8th of April 1945, Cologne is liberated by the American army.
1945 Böll is released from captivity as a POW in September. He joins his pregnant wife in Much. His son Christoph, who was born in July, dies in October due to the harsh conditions.