1427 was a common year starting on Wednesday.
- 16 May: Some 300 people in the settlement of Zatram, mostly Muslims, are massacred by the Venetians, marking the start of the War of Independence
- May-June: The Convention of Grijzestad met at the Grijzestad Market Hall, where they Declared Brunant's independence and created a constitution for the nascent Brunanter Republic
- July: The Walls of Grijzestad are begun
- 4 July: Niesburg is besieged and looted by Venetians
- 9 July: Marten Sneijder is elected first president of the Brunanter Republic
- 19 September: Battle of Brunant
- November to February 1428: the Siege of Brezonde occurs, marking the end of the War of Independence