From one whistle-blower in exile to another in a military prison comes a birthday greeting. Edward Snowden marked the 27th birthday of Chelsea Manning yesterday with a personalised message that praises the WikiLeaks source for having "inspired an angry public". Since he astounded the world with his revelations about the US National Security Agency in June last year, Snowden's name has perhaps inevitably been associated with that of Manning who similarly astounded the globe with the WikiLeaks trove of state secrets three years previously. In the pantheon of contemporary US official leakers, Snowden and Manning rank supreme - they were jointly nominated for the Nobel Peace Prize and Snowden has referred to Manning as "a classic whistle-blower". Now Snowden has offered words of comfort for Manning as she marks her fifth birthday behind bars. From his own exile in Russia, the former NSA contractor thanked Manning for her "extraordinary act of service", regretting that "it has come with such an unbelievable personal cost". He wrote: "You have inspired an angry public to demand a government that is accountable for its perpetration of torture and other war crimes, for the true costs of its wars, and for conspiring in corruption." Snowden's greetings are among a slew of birthday messages from artists, writers and activists published by The Guardian newspaper. As the Nobel prize-winning novelist J.M. Coetzee puts it: "I'm sure it is not much fun spending your birthday behind bars, but I want to let you know that there are thousands and millions of people in the wider world who are thinking of you and wishing you well." Michael Stipe, formerly of the band REM, sends a handwritten note headlined: "Hey Patriot!" He says "a lot of friends and supporters are thinking of you today". Filmmaker Terry Gilliam offers a cartoon of a figure tentatively stepping onto a tightrope over a cliff with the words: "Chelsea, your bravery has shown us much to be worried about. We are deeply in your debt." Manning, who changed her name from Bradley to Chelsea by petition in April as part of her gender transition, is serving a 35-year sentence for her transfer of massive databases of secret documents to WikiLeaks in 2010. The digital stash included videos of civilians being killed in Baghdad by a US attack helicopter, war logs from Iraq and Afghanistan that exposed the costs of America's wars, and US embassy cables from around the world that helped instigate the Arab spring while embarrassing the Washington establishment. Manning is being held in a military prison in Kansas.