Commonwealth of Australia
Who & why: the six British colonies — New South Wales, Victoria, Queensland, South Australia, Western Australia, and Tasmania — vote by referendum to federate, becoming the Commonwealth of Australia on 1 January 1901. A public design competition that same year produces the winning flag; the Commonwealth government formally fixes it in law as the Australian National Flag under the Flags Act 1953, effective 1954, with no change to the design itself.
What it represents: the Union Jack in the canton marks the federation's origin within the British Empire and Commonwealth; the large Commonwealth Star below it had six points for the six states in 1901 and gained a seventh, for the territories, in December 1908; the stars on the fly form the Southern Cross, which can be seen from all of Australia's states and territories.
Wikipedia says a federal flag competition of April 1901 drew 32,823 entries, the winning design first flew over the Royal Exhibition Building in Melbourne on 3 September 1901 with five near-identical entries sharing the prize, Edward VII's approval was announced on 11 February 1903, the Southern Cross stars were standardised to seven points on 23 February 1903, the Commonwealth Star gained a seventh point on 8 December 1908, and the Flags Act 1953 received royal assent on 14 February 1954. FOTW (Morris) says the competition was announced in the Gazette of 29 April 1901, the flag first flew on 3 September 1901, the King's approval was given in 1902 and confirmed by a proclamation of 20 February 1903, a seventh point was added by the Gazette of 19 December 1908, and the Flags Act 1953 was confirmed in a Gazette of 14 April 1954.
- Flag of Australia — Wikipedia compiled
- Australia — Flags of the World (CRW Flags) compiled
Not established: The sources differ on the 1908 date (8 or 19 December), the 1903 dates, and the 1954 date (14 February assent or 14 April gazette). This page used to say the star was seven-pointed from the start.