Events in History
- May 17 Earl Johann Tilly attacks Maagdenburg
- May 18 English colony Massachusetts Bay grants puritarian voting right
Election of Interest
May 18 John Winthrop is elected 1st Governor of the Massachusetts Bay Colony

John Winthrop
- May 20 Magdeburg in Germany seized by forces of the Holy Roman Empire under earl Johann Tilly, most inhabitants massacred, one of the bloodiest incidents of the Thirty Years' War
- May 30 The Treaty of Fontainebleau signed between Maximilian I, Elector of Bavaria, and the Kingdom of France, establishing a secret alliance between them during the Thirty Years' War.