The year 1331 and the black death....
March 1st 1331 On this day in history black Death in Europe, Asia and North Africa killing 75-200 million (10-60% of European population) people.
The Gregorian calendar is 13 days ahead of the Julian calendar
Counting the end date....
From and including: Sunday, March 1, 2020
To and including: Friday, March 13, 2020
Result: 13 days