Historical Events in September 1400
- T 1
- F 2
- S 3
- S 4
- M 5
- T 6
- W 7
- T 8
- F 9
- S 10
- S 11
- M 12
- T 13
- W 14
- T 15
- F 16
- S 17
- S 18
- M 19
- T 20
- W 21
- T 22
- F 23
- S 24
- S 25
- M 26
- T 27
- W 28
- T 29
- F 30
- Sep 16 Owain Glyndŵr is declared Prince of Wales by his followers
- T 1
- F 2
- S 3
- S 4
- M 5
- T 6
- W 7
- T 8
- F 9
- S 10
- S 11
- M 12
- T 13
- W 14
- T 15
- F 16
- S 17
- S 18
- M 19
- T 20
- W 21
- T 22
- F 23
- S 24
- S 25
- M 26
- T 27
- W 28
- T 29
- F 30
List of Years