Colonial history of Nigeria is a complex and multifaceted topic, with the creation of Lagos as a colony in 1861, not 1865, being a pivotal moment in the country's development. This  note  will focus on the colonial history of Nigeria, and  the creation of Lagos as a colony:

In the mid-19th century, the British Empire was expanding its territories in West Africa, and Nigeria was a key region of interest. The British had been involved in the transatlantic slave trade, and after its abolition, they turned their attention to the exploitation of natural resources and the establishment of trade relationships with local kingdoms.

The Creation of Lagos as a Colony
In 1861, the British government annexed Lagos, which was then a small kingdom, and declared it a colony. This move was motivated by the desire to establish a strategic foothold in West Africa, control the slave trade, and expand British trade and influence in the region. The annexation of Lagos was facilitated by the British bombardment of the city in 1851, which led to the signing of a treaty between the British and the King of Lagos, Dosunmu.

Treaty of Cession
The Treaty of Cession, signed on August 6, 1861, marked the formal beginning of British colonial rule in Lagos. The treaty transferred sovereignty over Lagos to the British Crown, and Dosunmu was recognized as the king of Lagos, subject to British authority. The treaty also established the boundaries of the colony and provided for the administration of justice, taxation, and other aspects of governance.

Colonial Administration
The British established a colonial administration in Lagos, with a governor as the head of the colony. The governor was responsible for implementing British policies, collecting taxes, and maintaining law and order. The colonial administration also established a system of courts, schools, and other infrastructure to support the growth of the colony.

Impact of Colonial Rule
The creation of Lagos as a colony had significant impacts on the region and its people. The British imposed their language, culture, and values on the local population, leading to the suppression of indigenous cultures and traditions. The colony also became a hub for trade and commerce, attracting people from all over West Africa and beyond. However, the exploitation of natural resources and the imposition of forced labor and taxation led to widespread poverty, inequality, and social unrest.

Expansion of British Influence
The creation of Lagos as a colony marked the beginning of British expansion in Nigeria. Over the next several decades, the British extended their control over other parts of the country, using a combination of military force, diplomacy, and strategic alliances with local leaders. The British eventually established the Colony and Protectorate of Southern Nigeria in 1906, which merged with the Northern Nigeria Protectorate in 1914 to form the modern Nigerian state.

Legacy of Colonial Rule
The legacy of colonial rule in Nigeria is complex and contested. While the British brought modern infrastructure, education, and healthcare to the region, they also imposed their own systems of governance, economy, and culture, which often marginalized and exploited the local population. The creation of Lagos as a colony in 1861 set in motion a chain of events that would shape the course of Nigerian history, leading to the country's independence in 1960 and its ongoing struggles with development, democracy, and identity.