Defence Minister Karl-Theodor zu Guttenberg, who had a relative with links to the resistance, led a wreath-laying ceremony at a memorial in his ministry's Bendlerblock courtyard, where some of the conspirators were executed.
Later Tuesday, he and Chancellor Angela Merkel were to observe the swearing-in in front of the Reichstag parliament building of about 420 recruits to the military, which has carefully tended the memory of the July 20 plotters.
"The women and men of the resistance set ethical standards with their actions and became role models," Mayor Klaus Wowereit said at the Bendlerblock ceremony.
The July 20 plot, as it has come to be known, was led by an aristocratic army officer called Count Claus Schenk von Stauffenberg, who wore a patch to cover an eye lost in battle.
Stauffenberg placed a bomb under a table in Hitler's eastern headquarters in East Prussia, in modern-day Poland. But the Nazi leader escaped with slight injuries because the briefcase carrying the explosives was moved by chance behind a sturdy oak leg of the table.
Confusion reigned 700 kilometres (435 miles) away in Berlin, with conflicting information about whether Hitler had survived the attack, but it soon became clear that the plot had failed.
Co-conspirator Philipp von Boeselager was meant to return from the Eastern Front with 1,200 men and overthrow the clique at the head of the Third Reich, which had unleashed the catastrophic war and the Holocaust.
Stauffenberg and several others were executed the same evening in the Bendlerblock courtyard, part of a complex of buildings where the plot was hatched.
The episode was turned into a recent movie called "Valkyrie" with Tom Cruise playing the part of Stauffenberg.
Historian Fritz Stern said at the Bendlerblock ceremony Tuesday the assassination attempt had been unique in German history.
"Never before had there been such an uprising for liberation, justice and human dignity in Germany," he said.
That the plot failed is seen as one of the tragedies of World War II as millions more people were killed on the battlefield and in the gas chambers before Hitler was defeated in 1945.