Don Antonio Marcaccini was a leading player in the war in the Conca Valley. Partly thanks to the presence of the communist Gianni Quandamatteo, he succeeded in building an important anti-fascist presence in the area. The efforts deployed by the resistance in that area were extensive, and in Farneto, Decio Mercanti, an important member of the Rimini Cln also spent time in hiding in the parsonage of Don Marcaccini while escaping from the fascists.

The attendance of those places led Mercanti to ask the CUMER (Comando unico militare Emilia Romagna - Single Military Headquarters of Emilia Romagna) representative to make an inspection to check whether a partisan brigade could be set up in lower Romagna. The suggestion was rejected on the grounds that the area was not suitable for holding a large number of partisans. In early July, the priest was involved in the assault on the town of Gemmano in order to break up the population register to avoid the republican draft. During the raid, a number of documents and blank identity cards sent to CUMER in Bologna were also taken.

However, the episode for which Don Marcaccini became famous occurred on 6 September 1944, when the Germans were after Gianni Quondamatteo, who escaped from the rectory and sought refuge in a gully in the Ventena stream. As retaliation, the Germans seized six men from neighbouring shelters and threatened them with firing squads for helping Quondamatteo escape. The parish priest, don Antonio Marcaccini, tried to save them by explaining that Quondamatteo was not a partisan and that they were innocent. After fruitless attempts, don Marcaccini volunteered in place of the 6 to be shot; the gesture convinced the German officer to free the hostages and leave the village.