Italian Watch Tower believers between America and Italy
An international convention was held at Columbus, Ohio, July, 20 to 27, 1924. It was international in two senses: First, in that it was a convention of Watch Tower believers who spoke various languages; and secondly, people were expected to attend from various countries throughout the earth . The Watch Tower expected that it should be the largest convention of Bible Students ever held on earth .
About the foreign-speaking people we read:
In the United States and Canada there is a number of foreign-speaking brethren, Germans, Greeks, Lithuanians, Poles. Ukrainians, Slovaks, Hungarians, Italians, etc. It will be expected that the brethren of these foreign languages will attend, and that all the Pilgrim brethren who serve the foreign-speaking brethren will also attend. Meetings of the brethren speaking each of the languages will be conducted regularly. There will be no distinction in race, color or language, but all will be one in Christ. 
In June, Richard A. Johnson and Rutherford toured Great Britain and parts of continental Europe to advertise the International Convention at Columbus. They hoped that the Bible Students would come from the four corners of the earth. 
Columbus was chosen because of its location, being the most accessible to the largest number of people; because of the transportation facilities and street-car accommodations; because of the number and size of the available auditoriums. They rented the largest stadium for the public witness.
The Ohio State Journal carried a four-page report daily of the Convention. .
A detailed report of that convention appeared in The Watch Tower of September 1, 1924, pp. 259-264. Three months later the same article appeared in the Italian edition of the magazine,  but with a little difference: at page 165 we find a picture of Rutherford together with De Cecca and a group of Italian-American Bible Students. 
The first Convention held in Italy was at Pinerolo, Piedmont, April 23 to 26, 1925. About sixty people attended the convention, five men and eight women were baptized; the speakers were Remigio Cuminetti, G. Maurelli, M. Martinelli and A. H. Macmillan.
A later report reads:
The work continued to expand in spite of many difficulties, and the first assembly was held at Pinerolo April 23 to 26, 1925. Since Brother A. H. Macmillan from the Society’s headquarters was making a series of visits abroad, he was able to be present. The assembly was held in a large room at the Corona Grossa hotel.
It would have been ridiculous to expect the Fascist authorities to give their permission for this assembly. So the brothers disguised the gathering as a wedding celebration. During the assembly Brother Remigio Cuminetti married Sister Albina Protti, one of the Swiss colporteurs. At that historic assembly there were 70 in attendance and 10 of these were baptized.
“Our days were full of blessings, rejoicing and happiness,” wrote Sister Brun, who was present at the assembly. She adds: “The hotel owner brought his other guests and clients into the hall saying: ‘Come and see everybody, we have the primitive church under our roof!’ . . . Everything was well organized and we usually managed to clear the floor and set the chairs out in a flash. Afterward we would put them away again and leave everything in order. We were all happy and willing to lend a hand. It was a great witness.”
Nevertheless, during that first assembly there was a curious inconvenience. “Although we were very different in many ways, we managed to get on well together. However, we did not manage to agree on the singing of the songs. The brothers from the north sang with a lively rhythm, while those from the south sang slowly and with such feeling that it was a pity to make them change. So the presiding brother decided to have those from the south of Italy sing first, followed by those from the north.” 
The presence of Macmillan is confirmed in the original Italian Watch Tower, even though, in the picture taken after the convention we can’t see him; probably he had only just left. 
 WT May 1 1924, p. 138, “International Convention”, paragraph 2
 WT May 15 1924, p. 147, “International Convention” at Columbus”
 WT June 1 1924, p. 164, “Foreign Languages”
 WT June 1 1924, p. 171, “The International Convention at Columbus”
 WT August 1 1924, p. 226, “Convention Report”
 La Torre di Guardia, November 1924, p. 163, “La Convenzione internazionale”
 La Torre di Guardia, November 1924, p.165
 Yearbook 1982, pp. 133-4
 La Torre di Guardia, August 1 1925, p. 121.