The outbreak of the Second World War in September 1939 did not initially cause much disruption in Gibraltar, as Spain and Italy were neutral at the time. The situation changed drastically after April 1940 when Germany invaded France, with Italy joining the invasion in June 1940. The British Government feared that Spain would also enter the war and it was decided to evacuate the entire civilian population of Gibraltar in May 1940. Most went to the United Kingdom and others to Madeira and Jamaica, while some made their own way to Tangier and Spain. An intensive programme of tunnelling and refortification was undertaken; over of tunnels were dug in the Rock, and anti-aircraft batteries were installed in numerous locations in the territory. A new and powerful naval group called Force H was established at Gibraltar to control the entrance to the Mediterranean and support Allied forces in North Africa, the Mediterranean and the Atlantic. The airfield, which was now designated RAF North Front, was also extended using soil from the tunnelling works so that it could accommodate bomber aircraft being ferried to North Africa. The garrison was greatly expanded, reaching a peak of 17,000 in 1943 with another 20,000 sailors and airmen accommodated in Gibraltar at the same time.