Syria's civil war built upon sectarian conflicts elsewhere, especially in Iraq and Lebanon, leading to a growing sense across the region that all those power struggles in individual countries were part of a titanic battle for the future.
Abbas, a 24-year-old Iraqi Shi'ite fighter, said he knew he was living in the era of the Mahdi's return when the United States and Britain invaded Iraq in 2003.
"That was the first sign and then everything else followed," he told Reuters from Baghdad, where he said was resting before heading to Syria for a fourth time.
"I was waiting for the day when I will fight in Syria. Thank God he chose me to be one of the Imam's soldiers."
Abu Hsaasan, a 65 year old pensioner from south Lebanon, said he once thought the prophecies of the end of days would take centuries to come about.
"Things are moving fast. I never thought that I would be living the days of the Imam. Now, with every passing day I am more and more convinced that it is only a matter of few years before he appears."