On November 9, 1989, East German official Günter Schabowski walked into a routine press conference holding a sheet of notes he hadn’t properly read.

The East German government had drafted a plan to gradually relax travel restrictions... - The Historian's Den

...a slow, controlled process meant to unfold over weeks. 

But when a reporter asked when the new rules would take effect, Schabowski flipped through his papers, confused, and casually replied: 

“As far as I know… it takes effect immediately.”

• He wasn’t supposed to say that. 
• The policy wasn’t finalized, the border guards weren’t informed, and nothing was prepared...READ ALL!!