HAMBURG, Germany — The rebuff from Berlin may have been rough, but at least it marked a new age of clarity. Not only did the German government decline a recent American request to send ground troops to Syria to fight the remnants of the Islamic State, but it didn’t even consider the idea: There was no debate in the Bundestag, and not even a real one in the press.

This year, Germany’s postwar federal republic turns 70. Born from the moral and physical rubble of World War II, and reunited only 30 years ago, some of its national character traits are still being formed. Others have fully matured — including a deep and abiding anti-militarism.

Germany didn’t start out on this path alone. After 1945, having crushed the Nazi regime, the Western allies granted West Germany its own army, but only as a deterrent against the Soviet Union. It was fully integrated into NATO, with no general staff of its own. Instead, Bonn paid upkeep for the American troops stationed in West Germany. From the start, responsibility for national security was outsourced to others.

At the same time, Germans began to come to grips with the moral horror of the Nazi era. One conclusion from that reckoning was a deep aversion to military strength — for many Germans, particularly in the generation born immediately after the war, their unshakable guilt meant they could never be trusted with the power to make war.