Original sentence: However, in 1922, following the War of Independence (19191921) and the Anglo-Irish Treaty, the southern and western part became the Irish Free State, while Northern Ireland exercised its option to remain in the United Kingdom.It took place on 3 May 1921 under the Government of Ireland Act 1920.The smaller of the two, Northern Ireland, was duly created with a devolved administration and forms part of the United Kingdom today, but the larger one, intended as a home rule jurisdiction to be known as Southern Ireland, failed to gain acceptance.The territory instead  became independent and is now a sovereign state also named Ireland and additionally described as the Republic of Ireland
Edited sentence: However, in 1922, following the War of Independence (19191921) and the Anglo-Irish Treaty, the southern and western part became the Irish Free State.Northern Ireland remained under British occupation