Two prominent newspapers this week used their editorial pages to call for mercy for intelligence leaker Edward Snowden, with one arguing "he deserves better than a life of permanent exile, fear and flight."

The New York Times and The Guardian make the case for some sort of plea deal or clemency that would allow Snowden to return to the United States from Russia, where he was granted asylum.

Mercy or dropped charges have occurred in past cases of other high-profile whistle-blowers, such as Daniel Ellsberg, the military analyst behind the leak of the Pentagon Papers. But in recent years, the United States has aggressively pursued those who leak government secrets.

Here's a look at how the cases of five prominent leakers -- including Snowden -- have played out:

Daniel Ellsberg

Ellsberg was the military analyst who leaked the 7,000-page Pentagon Papers in 1971.

The top-secret documents revealed that senior U.S. leaders, including three Presidents, knew the Vietnam War was an unwinnable, tragic quagmire. Further, they showed the government had lied to Congress and the public about the progress of the war.

Ellsberg surrendered to authorities and was charged as a spy.

During his trial, the court learned that President Richard Nixon's administration had embarked on a campaign to discredit Ellsberg, illegally wiretapping him and breaking into his psychiatrist's office. All charges against him were dropped. Since then, he has lived a relatively quiet life as a respected author and lecturer.

Chelsea Manning

U.S. Army Pvt. Chelsea Manning, who formerly went by the name Bradley, was convicted of stealing and disseminating 750,000 pages of classified documents and videos to WikiLeaks, the online anti-secrecy group.

1. who is Ellsberg?
2. what did the papers reveal?
3. when were the papers released?
4. what did Nixon do to him?
5. what did Nixon do to Ellsberg to discredit him?
6. did Ellsberg go to jail?
7. why not?
8. what happened to the charges?
9. where is Edward Snowden living now?
10. why?
11. who is calling for mercy for him?

Provide a numbered list of answers.
1. military analyst behind the leak of the Pentagon Papers
2. presidents knew that the Vietnam War was an unwinnable, tragic quagmire
3. 1971
4. unknown
5. wiretapped him and broke into his psychiatrist's office
6. no
7. Because the tactics used against him were illegal
8. they were dropped.
9. Russia
10. He was granted asylum there.
11. The New York Times and The Guardian