Complex sentence: The first immigrants arrived at Holdfast Bay (near the present day Glenelg) in November 1836, and the colony was proclaimed on 28 December 1836, now known as Proclamation Day.
Split into simpler sentences: The first immigrants arrived at Holdfast Bay (near the present day Glenelg) in November 1836. The commencement of colonial government was proclaimed on 28 December 1836, now known as Proclamation Day.