Final answer:
The First Fleet arrived in Sydney Harbour on January 26, 1788, marking the establishment of the first European colony in Australia, which is now commemorated as Australia Day.
Step-by-step explanation:
The First Fleet is the name given to the group of ships that carried the first European settlers to Australia. This fleet, consisting of 11 vessels, set sail from Portsmouth, England, on May 13, 1787, and arrived at Botany Bay between January 18 and January 20, 1788. After exploring the area around Botany Bay and deeming it unsuitable for settlement, they moved north to Port Jackson, which is where Sydney Harbour is located today. The fleet arrived in Sydney Harbour on January 26, 1788, which is now celebrated as Australia Day, a national holiday in Australia commemorating the establishment of the first European colony at Sydney Cove.