Ireland's historic observatories at Armagh and Dunsink near Dublin, founded in the eighteenth century, were distinguished centres of astronomy for well over a hundred years. The twentieth century, however, saw a sad decline in their fortunes. Armagh survived, but without its early scientific prestige; Dunsink virtually ceased to function in 1921 and closed completely in 1937. Astronomy in Ireland was effectively nonexistent. Then, in 1946, after World War II ended, Dr Eric Lindsay, the recently appointed Director, commenced a bold programme of modernization at Armagh Observatory. In the following year, the Irish Government in Dublin re-established Dunsink Observatory under the auspices of the Dublin Institute for Advanced Studies, and in response to an initiative of Eric Lindsay's, the two observatories set up a collaboration with Harvard in the United States to share a telescope in South Africa, the first ever such international venture in the history of astronomy. Dr Lindsay was also a believer in engaging the wider public in the Observatory's work, and through his encouragement the amateur Irish Astronomical Society which flourished in Dublin since 1937, expanded into a successful all-Ireland organization in 1947. These remarkable developments were due in a great measure to the vision and energy of Eric Lindsay and led to a renaissance of astronomy in Ireland.