Reasons:
Trade/ economics: further trade possible given new routes inland and subsequent discovery of minerals and resources. Investments. Agriculture. Coal, iron, timber. Needed to meet demands of British industry.
Personal influence:
Merchant-imperialists, Goldie, Rhodes, capitalised on new commodities finding fortune.
Strategy:
Morality:
Missionaries saw it as their moral duty to spread Christianity throughout Africa. Empire was a force for 'civilisation'. Livingstone went in 1858 to 'open a path for commerce and Christianity'.
Exploration:
Explorers found commodities which they were able to exploit such as gold, diamonds and palm oil.