On 22 April 1945, the Soviet Army entered Berlin. Some reports held that Adolf Hitler then suffered from a nervous breakdown, but certainly he knew from this point that his own fate was sealed. (PROSE: The Shadow in the Glass)
On that day, River Song emerged from the lake in a space suit, and supposedly killed the 1103-year-old Eleventh Doctor before he was able to regenerate. In reality, the Doctor was in the Tesselecta during the murder, and remained unharmed during the whole process. (TV: The Impossible Astronaut, The Wedding of River Song)
The Doctor, at age 1103, recruited via numbered envelopes a 909-year-old version of himself (1), an older River Song (2), Amy Pond and Rory Williams (3), and Canton Everett Delaware III (4) to witness the event. All arrived in Utah and, except for the younger Doctor, met up with the older Doctor. After his supposed death, they set fire to what they thought was his body, and let it float away on a boat.
An alternate timeline was created when River instead exhausted the weaponry of the astronaut suit, and didn't "kill" the Doctor. Immediately, a new reality came into being where all of history happened at once, and the time remained 5:02 PM on 22 April 2011 forever. In this reality, the Eleventh Doctor and River Song got married, so he could discreetly reveal to her that he was actually on-board the Tesselecta. The timeline was reverted when the Tesselecta and River, the opposite poles of the disruption, kissed, the proximity shorting out the differential, and letting time continue its course. (TV: The Wedding of River Song)