The Union Flag 1770
union flag
Australia′s first flag was the Union Flag (used by Captain Cook in 1770 and Captain Phillip in 1788).

The Union Jack 1801
Union Jack
Then came the Union Flag (also known as the Union Jack) with the inclusion of the flag of St Patrick when Ireland joined the Union in 1801.

Australian Flag 1901 – Defaced British Red Ensign
Australian Flag 1901
From the middle of the nineteenth century, a growing Australian nationalism brought forth many unofficial flags – all of them incorporating the constellation of the Southern Cross (Crux Australis), which was universally accepted as the emblem of the Great South Land.
In 1901 the new Federal Government organised a competition for a new flag – one for "official" or Government use, and one for the "merchant" service (i.e. citizens at sea). The judging and approval process were such that only a British Ensign with a badge representative of Australia was likely to be a winner.
The winning design for the merchant flag was based on the British Red Ensign, and the winning design for the official Government flag was based on the British Blue Ensign.

Australian Flag 1903 – Stars Altered in Southern Cross
Australian Flag 1903
The King approved slightly altered designs in 1903, and the Union Jack was to remain the senior flag to both designs.

Australian Flag 1909 – Seventh Point Added to Federation Star
Australian Flag 1909
Then, in 1909 a seventh point was added to the Federation star.

Australian Flag 1953 – Defaced British Blue Ensign
Australian Flag 1953
For many years there was considerable misunderstanding in Australia and in other countries with regard to the use of the Australian flags. During World War II, Prime Minister Menzies issued a directive that there should be no restriction on the flying of the "Commonwealth Blue Ensign", and Prime Minister Chifley gave his support to that view in 1947. In 1953, by means of a Commonwealth Act of Parliament – the Flags Act 1953 – the "British Blue Ensign" was proclaimed the national flag. Only since then has it had seniority over the Union Jack.