The Battle of Knockdoe was a battle that took place on 19 August 1504 at Knockdoe, in the Parish of Lackagh (Irish Leacach), County Galway, between two Anglo-Irish lords—Gerald FitzGerald, Earl of Kildare, the Lord Deputy of Ireland, and Ulick Fionn Burke, lord of Clanricarde—along with their respective Irish allies. The cause was a dispute between Maelsechlainn mac Tadhg Ó Cellaigh (Mod. Irish Maoilseachlainn mac Thaidhg Uí Cheallaigh), King of Ui Maine – Mod. Irish Uí Mháine) and Clanricarde.The major contemporary sources for this battle are the Gaelic Irish annals and a sixteenth-century manuscript written in the Pale known as "the Book of Howth".