FORT MEADE, Md. — Army Pfc. Bradley Manning was sentenced today to 35 years in prison for giving hundreds of thousands of secret military and diplomatic documents to WikiLeaks in one of the nation’s biggest leak cases since the Pentagon Papers more than a generation ago.

Flanked by his lawyers, Manning, 25, stood at attention in his dress uniform and showed no reaction as military judge Col. Denise Lind announced the punishment without explanation during a brief hearing.

The former intelligence analyst was found guilty last month of 20 crimes, including six violations of the Espionage Act, as part of the Obama administration’s unprecedented crackdown on media leaks. He was acquitted of the most serious charge, aiding the enemy, an offense that could have meant life in prison without parole.

Manning could have gotten 90 years behind bars. Prosecutors asked for at least 60 as a warning to other soldiers, while Manning’s lawyer suggested he get no more than 25, because some of the documents he leaked will be declassified by then.

He will get credit for the more than three years he has been held but will have to serve at least one-third of his sentence before he is eligible for parole. He was also demoted to private and dishonorably discharged.