On 1 December 1918, Denmark recognized Iceland as a free and sovereign state when the Union Treaty took effect. The date bears huge significance and was arguably the most important steppingstone in the Icelandic campaign for self-determination. The treaty comprised that Icelanders would handle all their own affairs, apart from certain foreign matters.
Even though the country was ravaged by the Spanish Flu and was furthermore experiencing one of its coldest winters ever in 1918, this great achievement was duly celebrated on one cold December morning in Reykjavík and has been celebrated yearly ever since.
Happy Sovereignty Day!