St. Omer is a large town 45 kilometres south-east of Calais. Longuenesse is a commune on the southern outskirts of St. Omer. The Cemetery is approximately 3 kilometres from St Omer, beside the Wizernes (Abbeville) road (the D928), at its junction with the Rue des Bruyeres.
St. Omer was the General Headquarters of the British Expeditionary Force from October 1914 to March 1916. Lord Roberts died there in November 1914. The town was a considerable hospital centre with the 4th, 10th, 7th Canadian, 9th Canadian and New Zealand Stationary Hospitals, the 7th, 58th (Scottish) and 59th (Northern) General Hospitals, and the 17th, 18th and 1st and 2nd Australian Casualty Clearing Stations all stationed there at some time during the war. St. Omer suffered air raids in November 1917 and May 1918, with serious loss of life. The cemetery takes its names from the triangular cemetery of the St. Omer garrison, properly called the Souvenir Cemetery (Cimetiere du Souvenir Francais) which is located next to the War Cemetery. The Commonwealth section of the cemetery contains 2,874 Commonwealth burials of the First World War (6 unidentified), with special memorials commemorating 23 men of the Chinese Labour Corps whose graves could not be exactly located. Second World War burials number 403, (93 unidentified). Within the Commonwealth section there are also 34 non-war burials and 239 war graves of other nationalities. The cemetery was designed by Sir Herbert Baker.