Yugoslavia went through three distinct political incarnations in the twentieth century, and each one flew a version of the same flag. A royalist kingdom, a communist federation and a rump republic under international sanctions all used the blue-white-red horizontal tricolor; the only thing that changed was whether a red star sat in the middle. That makes the flag a rare thing: a single design whose small edits track the entire rise and fall of a country, from its optimistic assembly in 1918 to the day in 2006 when the last state calling itself Yugoslav quietly dissolved.
Three colors for one imagined nation
The colors predate the country by seventy years. At the Prague Slavic Congress of June 1848, delegates from Slavic peoples across the Habsburg lands adopted blue, white and red as shared pan-Slavic colors, borrowing them from the flag of Russia, the one independent Slavic great power of the day. Over the following decades the combination spread through the flags of Serbia, Montenegro, Croatia, Slovenia, Slovakia and others, each arranging the same three stripes in its own order.
When the Kingdom of Serbs, Croats and Slovenes was proclaimed on 1 December 1918, the pan-Slavic set was the obvious choice, and it carried a convenient arithmetic: Serbia flew red-blue-white, Croatia red-white-blue, Slovenia white-blue-red. A blue-white-red tricolor was a fourth permutation belonging to none of them individually, which suited a state trying to fuse three peoples into one "Yugoslav" nation. The kingdom, renamed Yugoslavia in 1929, flew the plain tricolor until the Axis invasion dismembered the country in April 1941.
The Partisans add a star
The flag's second life began in the mountains. Tito's Partisan resistance, the communist-led movement that fought the occupation and the collaborationist regimes, marched under the old tricolor with a red five-pointed star added: national colors plus the emblem of world communism, a compact statement of what the movement intended to build. The AVNOJ council, the Partisans' provisional government, used the starred flag from 1943, the year the Allies recognized the movement, and it flew over the new Yugoslavia's institutions from the moment of liberation.
The socialist federation made it official on 31 January 1946, the day of its first constitution. The design is credited to Đorđe Andrejević-Kun, the painter who also drew the state coat of arms: a 1:2 tricolor of blue, white and red with a red star, edged in narrow yellow, centered on the flag and overlapping all three stripes. Each of the six republics received its own flag on the same pattern, its national tricolor or red banner carrying the same bordered star. For 46 years the starred tricolor was the face of a state that positioned itself between the blocs, hosted the Non-Aligned Movement's founding summit in Belgrade in 1961, and put the flag on Olympic podiums and Adriatic package-holiday brochures alike.
Subtraction by legislation
The federation began coming apart in 1991, when Slovenia and Croatia declared independence, and each departing republic pulled the star off its own flag within months. Slovenia and Croatia replaced theirs with new coats of arms; Macedonia adopted a sun; Bosnia and Herzegovina started from scratch.
What remained, Serbia and Montenegro, proclaimed the Federal Republic of Yugoslavia on 27 April 1992. That same day in Belgrade, the starred flag came down and a plain blue-white-red tricolor went up, the kingdom's flag returned in 1:2 proportions. The timing gave the new flag a grim context: within weeks the FRY was under UN sanctions for the wars in Croatia and Bosnia, and the starless tricolor spent the 1990s attached to a state most of the world refused to seat at the UN under Yugoslavia's old membership. It flew through the NATO bombing campaign of 1999 and the fall of Slobodan Milošević in 2000.
One image from that era does not belong to this flag, though it is regularly misattributed. The protest flag with a hole cut in the middle, where a communist emblem used to be, is Romanian: demonstrators in December 1989 cut the socialist coat of arms out of Romania's tricolor, echoing what Hungarian revolutionaries had done in 1956. Yugoslavia's star was never cut out in the streets. It was removed by constitutional drafting, which is a much quieter way for a symbol to die.
The flag outlives the name, then doesn't
In 2003 the FRY restructured itself as the looser State Union of Serbia and Montenegro, dropping "Yugoslavia" from the map after 74 years. The flag stayed, an unusual case of a country changing its name and keeping a flag that no longer matched anything. The arrangement had a built-in exit clause, and Montenegro used it: after a May 2006 independence referendum, the union dissolved, and the tricolor was formally relinquished on 3 June 2006. Serbia reverted to its red-blue-white tricolor, Montenegro adopted a red banner with a golden eagle, and for the first time since 1918 no state on Earth flew a Yugoslav flag.
The starred version has had the livelier retirement. It appears at Partisan memorial sites like Sutjeska and Jasenovac, at anti-fascist anniversaries, at Workers' Day picnics, and in the sizable ex-Yugoslav diaspora, where it signals a supranational identity that outlived its state. Nostalgia for the socialist federation runs deep across the former republics, and the flag is that sentiment's principal prop. Whether that reads as warm memory or historical amnesia depends, like most things in the region, on who is looking at it.
References
[1] "Flag of Yugoslavia," Wikipedia, covering the kingdom, SFRY and FRY versions with specifications. https://en.wikipedia.org/wiki/Flag_of_Yugoslavia
[2] "Flag of Yugoslavia," Encyclopaedia Britannica, on the pan-Slavic origins and the 1992 removal of the star. https://www.britannica.com/topic/flag-of-Yugoslavia
[3] "Flag of Serbia and Montenegro," Wikipedia, on the 1992-2006 starless tricolor and its retirement on 3 June 2006. https://en.wikipedia.org/wiki/Flag_of_Serbia_and_Montenegro
[4] Associated Press photo archive, Belgrade, 27 April 1992: the starred flag replaced by the starless tricolor at the proclamation of the FRY constitution.
[5] Smith, Whitney. Flags Through the Ages and Across the World (1975). McGraw-Hill.