General Henri Guisan orders the Swiss Army to resist German invasion and makes surrender illegal.

The Swiss Armed Forces (German: Schweizer Armee, French: Arme suisse, Italian: Esercito svizzero, Romansh: Armada svizra; lit.'Swiss Army') operates on land and in the air, serving as the primary armed forces of Switzerland. Under the country's militia system, regular soldiers constitute a small part of the military and the rest are conscripts or volunteers aged 19 to 34 (in some cases up to 50). Because of Switzerland's long history of neutrality, the Swiss Armed Forces do not take part in conflicts in other countries, but do participate in international peacekeeping missions. Switzerland is part of the NATO Partnership for Peace programme.The regulations of the Swiss militia system stipulate that the soldiers keep their own personal equipment, including all personally assigned weapons, at home (until 2007 this also included ammunition), or in an armoury. Compulsory military service applies to all male Swiss citizens, with women serving voluntarily. Males usually receive initial orders at the age of 18 for military conscription eligibility screening. About two-thirds of young Swiss men are found suitable for service, while alternative service exists for those found unsuitable. Annually, approximately 20,000 persons are trained in basic training for 18 weeks (23 weeks for special forces).

The reform "Army XXI" replaced the previous model "Army 95" and was adopted by popular vote in 2003, reducing manpower from 400,000 to about 200,000 personnel, with 120,000 receiving periodic military training and 80,000 reservists who have completed their total military training requirements. A further reform effective in 2018 heralded the reduction of forces to 100,000 members.

Henri Guisan (French pronunciation: ​[ɑ̃ʁi ɡizɑ̃]; 21 October 1874 – 7 April 1960) was a Swiss army officer who held the office of the General of the Swiss Armed Forces during the Second World War. He was the fourth and the most recent man to be appointed to the rarely used Swiss rank of general, and was possibly Switzerland's most famous soldier. He is best remembered for effectively mobilizing the Swiss Armed Forces and Swiss people in order to prepare resistance against a possible invasion by Nazi Germany in 1940. Guisan was voted the fourth-greatest Swiss figure of all time in 2010.