11 April

11 April was a date.
In 1492, the Doctor defeated the Mandragora Helix in San Martino.In Beautiful Chaos, during a part of the book explicitly dated to 15 May 2009, the Mandragora Helix dates its encounter with the Doctor to 517 years, 1 month and 4 days previously. (TV: The Masque of Mandragora, PROSE: Beautiful Chaos)
In 1865, Abraham Lincoln gave his final public address in Washington DC in the wake of the end of the American Civil War. (PROSE: Blood and Hope)
In 2118, the Tenth Doctor and Rose Tyler found themselves in Chad, where the Wurms had just uncovered a trap of artistic treasure set for them by the Valnaxi about two thousand years earlier. (PROSE: The Art of Destruction)
In 4530, the human-Zarbi wars came to an end when Earth faced an insect-repellent shortage. (PROSE: Time Traveller's Diary)
==Footnotes==