9 October 19

In 1924, Hiram Percy Maxim, President of the American Radio Relay League, realized that amateur radio had become international, and that there should be a global organization to take advantage of that growth. He was also aware that radio frequencies thought to be of little use, which had been assigned to amateurs, were capable of long range communication with low power and simple antennas. This resulted in administrations reconsidering the reassignment of these frequencies from amateur use into commercial and military applications.

In March of 1924 Hiram P. Maxim met in Paris with an international group of talented radio amateurs from France, Great Britain, Belgium, Switzerland, Italy, Spain, Luxembourg, Canada and the USA which made preliminary plans for an international organization to be known as the International Amateur Radio Union (IARU). A Congress was arranged in Paris in April 1925 to create the permanent global amateur organization. Amateur Radio representatives of 23 countries then met in Paris to create the International Amateur Radio Union and to adopt a constitution.

While most of the 23 countries represented at the April 1925 meeting were from Europe, there were also delegates from North and South America, and from Japan. On April 17,1925 the first constitution of the IARU was unanimously adopted. At the final plenary session on April 18 some 25 countries were in attendance. All actions of the organizing Congress were approved and the International Amateur Radio Union was born, with Hiram P Maxim as its first President.

From the IARU history page and much more is on it IARU