This word arrived in the language in the 16th century, and quickly developed a range of senses. The one which has survived is "actuality", but in Early Modern English other senses were more dominant. The neutral idea of "something done" gained both positive and negative associations: a noble thing done or a bad thing done. The pejorative sense was commonest, and fact always has this connotation in Shakespeare. Murder, rape, cowardice, and other transgressions are all referred to as "facts". Gloucester describes the cowardice of Falstaff (the soldier) as an "infamous fact" (Henry VI Part 1 IV.i.30). Warwick cannot think of a "fouler fact" than Somerset's treason (Henry VI Part 2 I.iii.171).The rape of Lucrece is described as a "fact" to be abhorred (The Rape of Lucrece 349). And Lennox describes the way Duncan died as a "damned fact" (Macbeth III.vi.10). The old sense hasn't entirely disappeared, however. It will still be encountered in a few legal phrases, such as "confess the fact".
David Crystal is editor, with Ben Crystal, of Shakespeare's Words, published by Penguin