In August 1914, Lambe was appointed as captain of the seaplane carrier HMS "Hermes", which sank after being torpedoed in October of the same year. At the start of August 1916, having just been promoted to wing captain, Lambe took up appointment as the officer commanding the Royal Naval Air Service's Dover Command which included RNAS units at Dunkirk. During his time at the Dover Command, Lambe's aircraft carried out bombing raids on the German submarine harbours at Bruges. On 1 April 1918, Lambe was appointed General Officer Commanding the VII Brigade of the RAF. On 23 April, Lambe's VII Brigade carried out air attacks as part of the blocking of Zeebrugge and Ostend. On 9 May, Lambe was once again the air commander in a naval action, this time for the Second Ostend Raid.