Cap badge Royal Guernsey Light Infantry

The Royal Guernsey Light Infantry was an infantry regiment of the British Army that was formed from the Royal Guernsey Militia in 1916 to serve in World War I. They fought as part of the British 29th Division. Of the 2,280 men, most of whom came from Guernsey, who fought on the Western Front with the RGLI, 327 were killed and 667 were wounded.

Many Guernsey men had already volunteered for regiments in the British Army before the RGLI was formed. The RGLI was created because there was no Guernsey-named regiment to underline the island's devotion to the Crown.

The regimental motto, Diex Aïx, derives from the battle cry used by the Duke of Normandy 1,000 years earlier