Dietrich Bonhoeffer was 39 years old when he was hanged at Flossenburg concentration camp on April 9, 1945, at dawn. By then, the war's outcome was no longer in doubt. The Allies had crossed the Rhine. Berlin was encircled. The Red Army was within artillery range of the city. Bonhoeffer's execution -- ordered by Heinrich Himmler himself -- was not a military necessity. It was an act of personal vengeance against a man the Reichsfuhrer-SS had come to regard as a traitor of exceptional eloquence and therefore exceptional danger.

Bonhoeffer had not always been an assassination plotter. In his twenties, he had been a rising star of German Protestant theology -- brilliant, cosmopolitan, and confident. He studied in Berlin, Rome, and New York, where he served a brief stint as a student pastor at a Baptist church in Harlem and discovered American jazz, which he loved for the rest of his life. He became a professor at the University of Berlin at the age of 25, the youngest in the institution's history.

When the Nazis came to power in 1933, Bonhoeffer's theology -- which emphasized the costly grace of Christian discipleship and the obligation of believers to act in the world -- made his response immediate and unambiguous. He was one of the founders of the Bekennende Kirche (Confessing Church), which refused to submit to Nazi control of the Protestant churches. He preached against Hitler from the pulpit. He organized seminary training for young pastors outside the Nazi-aligned church establishment.

But Bonhoeffer's evolution from preacher to conspirator was gradual and agonizing. His Christian convictions initially made him hesitate about assassination -- the sixth commandment was clear. It was his reading of the Psalms, he later wrote, that resolved the paradox: when a tyrant has made the law itself into an instrument of evil, obedience to the law is no longer obedience to God. "Action comes out of stillness," he wrote in his journal in 1940. "I have found God in the silence."

Bonhoeffer's involvement in the assassination plots against Hitler operated through his contacts in the Abwehr (German military intelligence), which had become a nest of anti-Nazi conspirators. He used his church contacts as cover for intelligence-gathering trips to Switzerland and Sweden, where he passed information to Allied contacts. He helped two Jewish women escape from Germany through Switzerland. He was involved in planning the July 20, 1944, assassination attempt.

When the July 20 plot failed, the Gestapo began rounding up everyone connected to the conspirators. Bonhoeffer was arrested on April 5, 1943, at Finkenwalde Seminary. He spent the next two years in prison -- first in Berlin, then at Buchenwald, then at Tegel military prison, where he was held in a cell with a piano and was allowed to compose music and write theological treatises. His letters from this period, smuggled out by friends, are among the most beautiful documents of the war years.

At dawn on April 9, 1945 -- less than a month before Germany's surrender -- Bonhoeffer was taken from his cell at Flossenburg. He was led to a courtyard where an SS officer waited. He knelt and prayed briefly. He was then hanged on a meat hook. He was 39 years old.

He left behind a poem called Stations on the Road to Freedom, whose final stanza reads: "And free at last from all the fret of purposeless, long wandering, yes, such a death is a beginning rather than an end."