All history was a palimpsest

"If the Party could thrust its hand into the past and say this or that even, it never happened—that, surely, was more terrifying than mere torture and death." —pg 32

"Day by day and almost minute by minute the past was brought up to date. In this way every prediction made by the Party could be shown by documentary evidence to have been correct; nor was any item of news, or any expression of opinion, which conflicted with the needs of the moment, ever allowed to remain on record. All history was a palimpsest, scraped clean and reinscribed exactly as often as was necessary."

— Book One, Chapter 3