I have just discovered that one of my iCloud calendars has been deleted in the last week. I checked my time machine backup and found the folder for the deleted calendar in ~/Library/Calendars which contains all the events in the calendar. After creating a new calendar in the Calendar app I tried dragging and dropping all the events into it but after successfully importing they immediately vanished (one by one). How can I recreate the calendar from the files I have? Any help much appreciated.