Held in Geneva in a time period of August 2-7 of 1926, the also known as "Congress of Alienists and Neurologists of France and French-Speaking Countries" was a symposium-type gathering not ever held in this fashion before. It was inspired by a paper written by Henry Claude, a french psychiatrist on "Pre-Dementia and Schizophrenia". So big was the reputation of Claude that it moved his followers to get together just to hear him on this topic the day prior to the symposium. The August 1 meeting featured experts ranging from de Saussure, Laforgue, Hesnard, and Odier. All of these experts presented papers on schizophrenia mainly, and the superego.
The next year, the same groups met in Bloise, aiming to make a habit of meeting for professional purposes. The issue that ensued was that the second conference separated the experts into factions: Freudians versus the Institutional medical community led by the group's "secretary" Edouard Pichon.
The main issue that continued to arise was the definition of Psychoanalysis from an orthodox, Freudian, perspective versus the clinical, modern frameworks. This debate moved on to the 1960's, and the premise of the debate was that
"Psychoanalysis is not just some kind of a theory. It has a more precious and less debatable claim to fame: it has cured morbid states that hitherto resisted all therapeutic treatments."
Keep in mind that the first conference's influence in the field is that fact that the posterior conferences added more and more to the different hot topics of the time, namely, "conversion hysteria". Moreover, by the time the 6th conference came the International Psychoanalytical Association was sending good-will telegrams in support of the group, and the validity altogether of the field became more solid when the IPA began to attend the conferences. By 1933 the likes of Jean Piaget, de Sausurre, Lacan, and other great names in the field were put to debate during the conferences, creating more and more amazement and validity for these meetings.
Interestingly, the meetings were representative of their times. They represented a microcosmic strata of what society was then. For example, prior to WWII, the group was already speaking about genetics, masochism, and instinct, which were the particular hot topics of their time. The conferences ceased during the war, but the papers written during the time illustrated the behaviors that mostly manifested during the post-war years. This is historical and medical evidence of how society operated then. This is highly influential as a society.
The biggest influence of these conferences was that the stigma behind mental illness disappeared slowly behind the in-depth analysis of what causes things. There were factions developed, intellectual rivalry, jealousy, and reputations were made. However, the main importance of the Congress of psychoanalysts is the immense push that the field of psychology received just after the very first meeting was ever held.