On December 23, 1990, Slovenia held a plebiscite on whether to move towards independence from Yugoslavia. The question asked was: "Should the Republic of Slovenia become an independent and sovereign state?" (Ali naj Republika Slovenija postane samostojna in neodvisna država?).
The paper used in the plebiscite. Wikimedia
As reported in the New York Times the following day, some politicians worried that a vote for independence would lead to trouble in the other, more ethnically mixed Yugoslav republics. As Mile Šetinc, vice president of the Liberal Democratic Party, is quoted in warning against a yes vote: "There are lot of Croats in Bosnia-Herzegovina, and there are lots of Serbs in Croatia, so every involvement with those groups risks real civil war."
The official results were announced on December 26, with 94.8% of those who voted supporting independence, thus beginning a six-month countdown to independence being formally declared. This eventually took place on June 26, 1991, precipitating what would come to be known as the Ten-day War (desetdnevna vojna), lasting from June 27 to July 7, which, while securing Slovenia’s independence, also started the beginning of the much longer, and bloodier, Yugoslav wars.
Until 2005 the national holiday was known as Independence Day (dan samostojnosti), but in September of that year it was changed to Independence and Unity Day (Dan samostojnosti in enotnosti).