The 1865 United Kingdom general election saw the Liberals, led by Lord Palmerston, increase their large majority over the Earl of Derby's Conservatives to more than 80. The Whig Party changed its name to the Liberal Party between the previous election and this one.
Palmerston died in October the same year and was succeeded by Lord John Russell as Prime Minister. Despite the Liberal majority, the party was divided by the issue of further parliamentary reform, and Russell resigned after being defeated in a vote in the House of Commons in 1866, leading to minority Conservative governments under Derby and then Benjamin Disraeli.
This was the last United Kingdom general election where a party increased its majority after having been returned to office at the previous election with a reduced majority.
The 1865 general election was regarded by contemporaries as being a generally dull contest nationally, which exaggerated the degree of corruption within individual constituencies. In his PhD thesis, Cornelius O'Leary described The Times as having reported "the testimony is unanimous that in the General Election of 1865 there was more profuse and corrupt expenditure than was ever known before". As a result of allegations of corruption, 50 election petitions were lodged, of which 35 were pressed to a trial; 13 ended with the elected MP being unseated. In four cases a Royal Commission had to be appointed because of widespread corrupt practices in the constituency.