69 Cemeteries in France and Belgium

In the First World War, Margaret Holden joined the "Friends' Emergency Committee for the Assistance of Germans, Austrians and Hungarians in distress" which helped refugees of those countries stranded in London by the conflict. Charles Holden served with the Red Cross's London Ambulance Column as a stretcher-bearer transferring wounded troops from London's stations to its hospitals. Holden also served on the fire watch at St Paul's Cathedral between 1915 and 1917.

On 3 October 1917, Holden was appointed a temporary Lieutenant with the army's Directorate of Graves Registration and Enquiries. He travelled to the French battlefields for the first time later that month and began planning new cemeteries and expanding existing ones. Holden described his experience:

“The country is one vast wilderness, blasted out of recognition where once villages & orchards & fertile land, now tossed about & churned in hopeless disorder with never a landmark as far as the eye can reach & dotted about in the scrub and untidiness of it all are to be seen here & there singly & in groups little white crosses marking the place where men have fallen and been buried.”

 In September 1918, Holden transferred to the Imperial War Graves Commission (now the Commonwealth War Graves Commission) with the new rank of Major. From 1918 until 1928 he worked on 69 Commission cemeteries. Initially, Holden ran the drawing office and worked as the senior design architect under the three Principal Architects in France and Belgium (Edwin Lutyens, Reginald Blomfield and Herbert Baker). Holden worked on the experimental war cemetery at Louvencourt and, probably on the one at Forceville that was selected as the prototype for all that followed.

In 1920, he was promoted to be the fourth Principal Architect. His work for the Commission included New Zealand memorial to the missing at Messines Ridge British Cemetery (he also designed the cemetery), and the Post Office Rifles Cemetery at Festubert. His designs were often stripped of ornament, often using simple detailed masses of Portland stone in the construction of the shelters and other architectural element. Philip Longworth's history of the Commission described Holden's pavilions at Wimereux Communal Cemetery as "almost cruelly severe."