14–19 October 1946. Scientists from 16 different countries participated in this first post-war European optics conference. The invited papers were by Frank Twyman (of Hilger and Watts) on the production of aspherical surfaces; Louis de Broglie on image formation, Jean Cabannes on the development of optics in France, and Pierre Fleury reviewed the history of the Institut d'Optique and research pursued since 1940. Then followed several days of contributed papers from most of the European optics groups. Many of the participants urged Fleury to seek some mechanism for continued cooperation in the optics community. Pierre Fleury was already a French representative to IUPAP (the International Union of Pure and Applied Physics), with headquarters in Paris, and he was aware that the statutes of IUPAP provided for the creation of commissions in specific areas of physics; why not a commission for optics? He also determined that UNESCO (the United Nations Educational, Scientific, and Cultural Organization, with headquarters in Paris) would also be able to provide -through IUPAP- some funds for travel to a Preparatory Meeting in Prague to discuss the formation of an International Commission for Optics. The ICO Preparatory Meeting, Prague, Czechoslovakia, 1947 In January 1947 the General Assembly of IUPAP approved the appointment of a Preparatory Committee, with Prof. Pierre Fleury as Secretary, to consider forming an International Commission for Optics. The preparatory committee met in Prague, Czechoslovakia, 2–7 June 1947, with Prof Josef Hrdlicka as host. Fifteen delegates attended, representing eight countries, (Belgium, Czechoslovakia, France, Great Britain, Italy, the Netherlands, Poland, and Sweden). Replies were received from five other countries (Denmark, Finland, Norway, Switzerland, and the USA) that their representatives would be unable to attend, and Argentina and the USSR did not respond. The attendees agreed that an International Commission for Optics should be formed as a self-governing affiliated commission of IUPAP. Each member country would form a national committee for ICO, which would select that country's representative to the ICO Bureau meetings. A set of provisional Statutes was adopted (patterned after the Statutes of IUPAP), and a provisional bureau was elected, (subject to approval by IUPAP and re-confirmation by the national committees at the first official meeting.) Thomas Smith of London was elected president; Pierre Fleury of Paris, secretary; Albert Arnulf of Paris, treasurer; and Josef Hrdlicka of Prague a vice-president, with two other vice-presidents to be selected at the first official meeting. The delegates decided to