[Clara | Martha] But specifically, apparently there is this Gallifreyian 'weapon' known as The Moment, sentient in a way, formed a conscience. I guess the Doctor, though he tried to deny that part of him, took it the last day of the Time War. The Moment opened a fissure and so the Eleventh Doctor went through it, met up with the Tenth Doctor. There were Zygons. Anyway.... apparently it was so the War Doctor (I guess that works for figuring out between the three) wanted to see what choice he made, if it was the right one....
They were going to do it again, you know, not alone.... but I guess the Eleventh Doctor didn't like my look, asked a question and after some conversation, they figured out a way to save Gallifrey, even if they wouldn't remember because of Time/Space issues. They sent a message to each Regeneration through their Sonics to meet at that time and space and make Gallifrey disappear into a pocket dimension and the Daleks kill one another when it vanished.