Bonhoffer returned to Germany and began lecturing on theology in Berlin and wrote several books including Sanctorum Communio (1927) and Act and Being (1931). As he was a strong opponent of fascism he decided to leave Germany when Adolf Hitler gained power in 1933 and found work as a pastor in London.
On the outbreak of the Second World War the Gestapo closed down Bonhoffer's seminary and banned him from preaching. Over the next few years worked closely with other opponents of Adolf Hitler including Ludwig Beck, Josef Muller and Hans Oster.
In April 1943 Bonhoffer was arrested with his brother, Klaus Bonhoffer, and brother-in-law, Hans Dohnanyi and accused of plotting against Adolf Hitler. He was held in Buchenwald Concentration Camp until being moved to Flossenburg where he was executed in April, 1945. Ethics (1949) and Letters from Prison (1953) were published posthumously.