Charles Fremantle, aboard HMS Challenger, reached the coastline of what is now Western Australia in 1829. His arrival came at a crucial time when the British Empire was expanding its territories, driven by the desire for new resources and agricultural land. Upon anchoring at the Swan River, Fremantle carried out a formal proclamation asserting British sovereignty over the region. This act of declaration was not just a routine naval procedure; it was a strategic move aimed at establishing a foothold in Australia amid growing international competition. The decision was influenced by the successful colonization of nearby regions and stirred interest in the Swan River's agricultural potential.

Fremantle's proclamation initiated discussions about the future of the area, marking the beginning of the Swan River Colony’s establishment. His report indicated abundant natural resources and fertile land, which attracted settlers shortly after. The British government encouraged settlement to secure the area against potential rival claims, notably from the French who had shown interest in the region. As settlement commenced, Fremantle's arrival signaled the start of significant demographic and cultural changes in Western Australia, laying down the framework for future governance and land policies.

The Swan River Colony evolved due to the early challenges it faced, including resource shortages and conflicts with Indigenous peoples. It became a focal point for subsequent waves of immigration, leading to a diverse population. Fremantle’s role in the initial declaration marked him as an essential figure in the colonial history of Australia, highlighting a complex interplay of exploration, imperial strategy, and the ramifications of colonization on both settlers and Indigenous communities.