1720 in Ireland

Events

• March 26 – the Parliament of Great Britain passes the Dependency of Ireland on Great Britain Act 1719 , also known as the Declaratory Act 1720, declaring the right of the Parliament of Great Britain to legislate for Ireland and denying the appellate jurisdiction of the Irish House of Lords.
• Dr Steevens' Hospital is established at Kilmainham, Dublin.
• The Royal Cork Yacht Club is established as the Water Club of the Cork Harbour by William O'Brien, 4th Earl of Inchiquin; it is widely acknowledged as the world's oldest yacht club.
• Jonathan Swift publishes Proposal for Universal Use of Irish Manufacture.

Births

• October 1 – Hector Theophilus de Cramahé, Lieutenant-Governor of Province of Quebec, and Lieutenant Governor of Detroit
• October 9 – Andrew Lewis, pioneer, surveyor and soldier in Virginia
• October 18 – Peg Woffington, actress
• ;Full date unknown
• :*Patrick Browne, physician and botanist
• :*Ambrose Bernard O'Higgins, afterwards Ambrosio O'Higgins, 1st Marquis of Osorno, Spanish colonial administrator
• :*Seamus McMurphy, poet and outlaw

  Deaths

• August 18 – Matthew Aylmer, 1st Baron Aylmer, Admiral of the Royal Navy