War of the Quadruple Alliance: Great Britain declares war on Spain.
The War of the Quadruple Alliance (1718–1720) was caused by Spanish attempts to recover territories in Italy ceded in the 1713 Peace of Utrecht. Largely focused on Sicily, it included minor engagements in North America and Northern Europe as well as the Spanish-backed Jacobite rising of 1719 in Scotland.
In August–October 1717, Spain recaptured Sardinia from Habsburg Austria with little opposition, which it then followed by a landing in Sicily in July 1718. On 2 August 1718, a Quadruple Alliance was formed by Britain, France, Austria, and the Dutch Republic. The war ended with the 1720 Treaty of The Hague, which restored the position prior to 1717, but with Savoy and Austria exchanging Sardinia and Sicily.