The founding conference of Saor Éire was held #OnThisDay 26th September 1931.
The Left Republican group was banned later that year and collapsed shortly afterwards.
https://www.leftarchive.ie/calendar/on-this-day/09/26/#event-6290
On This Day, 26th September
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The 1931 ban included a number of Republican and communist organisations, as noted in this newspaper report.