
World War I (1914–1918) – Neutral Countries
These nations remained officially neutral throughout the war:
Switzerland
Sweden
Norway
Denmark
Spain
Netherlands
Luxembourg

(invaded and occupied by Germany but did not resist militarily)
Portugal

(initially neutral, joined Allies in 1916)
Albania

(collapsed into anarchy and was occupied)
Mexico
Argentina
Chile
Switzerland, notably, maintained a strict policy of armed neutrality.

World War II (1939–1945) – Neutral Countries
Several countries again declared neutrality, though some faced occupation or internal conflict:
Successfully Neutral Throughout WWII:
Switzerland

– maintained strict neutrality, despite being surrounded by Axis powers.
Sweden

– remained officially neutral but exported iron ore to Germany.
Ireland

– stayed neutral and did not allow British military use of its territory.
Portugal

– neutral but maintained diplomatic relations with both sides; part of the Iberian neutrality with Spain.
Spain

– under Franco, remained non-belligerent; supported Axis in some ways but never entered the war.
Turkey

– neutral for most of the war, joined the Allies in 1945 mainly as a symbolic gesture.
Vatican City

– neutral, but in the heart of fascist Italy.
Liechtenstein

– neutral with little involvement.
Andorra, San Marino, and Monaco – also nominally neutral microstates, but some experienced occupation or internal tension.
Neutral But Later Invaded or Pressured:
Belgium, Norway, Netherlands, Luxembourg – all declared neutrality but were invaded by Germany.
Denmark – neutral but invaded by Germany in 1940.

Key Notes:
Neutrality didn't always mean safety; some neutral countries were drawn in by invasion, internal pressure, or economic coercion.
Switzerland is the best example of consistent neutrality in both world wars.