During World War I the ICRC – and the Red Cross in general – came of age. While national societies provided ambulance volunteers and further support behind the lines, on a scale never before imagined, the ICRC expanded its work to protect prisoners of war.

It opened the International Prisoners-of-War Agency – a central clearing house for lists of prisoners and the provision of relief parcels. It also extended its work to include messages for civilians, after so many were cut off behind enemy lines.

In its quest to have humanitarian law adapted to new realities, the ICRC launched an appeal in February 1918, calling on the belligerents to stop using poison gas.