If event is deleted, it won't show in event history.
Click the event in the calendar and menu with different options will open. Click Edit history.
Window will open and shows when event is created, who has edited it and when it has been modified. Approving the event or event projects creates own record and in Is approved field shows lock icon. Created/modified time is set to be the time of the approval.
Clicking the View button will open the event with the data in that history time for a closer look.
In this article is more about restoring the events.