The Department of Justice knew there were likely to be major "sensitivities" around its plan for a commemoration for the Royal Irish Constabulary and Dublin Metropolitan Police months before the event was made public.
As controversy grew earlier this year, security fears emerged with the Office of Public Works [OPW] - which manages Dublin Castle where the event was due to take place - saying there would need to be "significant assistance" from the Garda.
"The gardaí have been in touch alright and they are very concerned," wrote an OPW official in an email to the department. "There have been serious protest/riot threats made."
Documents released by the Department of Justice under FOI also show just how closely involved Minister Charlie Flanagan was in helping organise the commemoration.
He even helped suggest music for the day, saying "Danny Boy, some Thomas Moore pieces, and anything else which the Garda Band would deem appropriate", according to internal emails.
The event ended up being deferred early in January and caused a major headache for Fine Gael in the run-up to the General Election.
Emails show the department knew last September that there were likely to be "sensitivities" around such a commemoration.
Internal records detail how controversy then started to build around January 2 when the department began receiving negative calls and complaints on Twitter.
An internal email said: "Not entirely surprising - it's a very sensitive area."
Another message sent to it said: "It is… trending on Twitter and the comments are not exactly favourable! Just type in 'Black and Tans' in the search box and you'll see what I mean."
The department tried to gather information to counteract some of the "nonsense circulating" about the event.
Speaking points prepared for the minister tried to hammer home the point that the event was not a "celebration" but was one of a large number of events due to take place this decade.
"This is not a commemoration of the 'Black and Tans' and the 'Auxiliaries' which briefly supplemented the RIC from 1920 to 1922," it said.
The department also received support from people who agreed the event should go ahead, especially from those with family who had served in either the RIC or DMP.
Following one such email, Minister Flanagan received a message from his special adviser saying: "There you go! Great to see it's not all one way traffic… did you send her a nice message back?"
Staff involved in the event were also reassured that the "deferral" of the event was not their fault.
A senior official wrote to his colleagues: "I appreciate the frustration that you must be feeling given the effort that went into it.
"I want to emphasise that the deferral of the event is absolutely no reflection on the quality of work done by the team, and this is recognised by everyone in the management team and the Minister's office."
The department was particularly annoyed about attempts to link the commemoration to the Black and Tans, internal emails show.
One message said: "This event was NOT planned as a commemoration of [them]… and it is quite ignorant of anyone to suggest otherwise."
The department had already sent out dozens of invitations to the event, with a very large number accepted and only a very small number declined for political reasons.
After deferring the event, the department received dozens of emails saying that they hoped the commemoration would take place at a later date, with the majority highly sympathetic to Minister Flanagan.