Grand Duchy of Luxembourg (restored)
Who & why: Luxembourg City is liberated by US troops on 10 September 1944, though the Battle of the Bulge pushes back into the country's northern Ardennes corner that December, and full liberation isn't complete until January–February 1945. Grand Duchess Charlotte, who spent the occupation broadcasting to her country from exile in London and Montreal, returns in April 1945. Luxembourg abandons its 19th-century neutrality for good, becoming a founding member of NATO in 1949 and, from the 1952 European Coal and Steel Community onward, one of the six founding states of what becomes the European Union — the country's capital now also hosting major EU institutions.
What it represents: the red-white-light-blue tricolor is the flag in use afterwards; the sources read do not describe the 1944/45 restoration itself. Wikipedia says the horizontal tricolor was fixed on 12 June 1845 (and "defined" in 1848, de facto) and that a 1993 regulation set the colours de jure; Flags of the World adds a flag law of 23 June 1972 and a 1993 regulation fixing the Pantone shades and proportions (3:5 or 1:2). The sources read do not support "1:1:2 proportions fixed in 1972" or a "first full legal description in 1848".
Wikipedia (Flag of Luxembourg): the horizontal red-white-light-blue tricolour was fixed on 12 June 1845, defined in 1848, and regulated by the law of 27 July 1993 (a 1972 emblems law was amended). Flags of the World (Luxembourg): flag law of 23 June 1972 and a 1993 regulation fixing the shades and proportions. Wikipedia (German occupation of Luxembourg): a photo caption shows civilians in Wiltz 'flying the flag of Luxembourg' at the liberation by US forces (liberation of the capital 10 September 1944).
- Flag of Luxembourg — Wikipedia compiled
- Luxembourg — Flags of the World (CRW Flags) compiled
- History of Luxembourg — Wikipedia compiled
- German occupation of Luxembourg during World War II — Wikipedia compiled
Not established: No source describes a formal 'restoration' in 1944/45; the 1944 start rests on the liberation dates and the photo caption. The sources differ on the de jure date (1993) and the 1972 law, and proportions were not checked.