The first inhabited group settled in Fossacesia in the ninth century, constituted by colonialists and craftsmen to the service of the abbey.
During the Roman Age other groups of colonialists, coming from the near region Lazio, decided to settle here. Inspired by the mild climate, the fertile fields, the plenty of clean waters and good pastures and thanks to the nearness to the Sangro River and the Adriatic Sea, the colonialists started to fish, hunt, trade and cultivate fields near the Abbey. They were encouraged also by the presence of the “tratturo”, a road used to graze animals linking the north part of the region with the south one and witness of important historical events that took place on this road. Along the tratturo, ruins of roman dwellings and Benedictine graves have been found. The port called “Portus Veneris”, situated to the mouth of Sangro River, was used to fishing and trading with other villages of the coast. Many people lived along the seaside, in small villages like Fossacesia linked each other by the Flaminia road, taking advantage by the products of the sea.
In the sixth century a group of byzantine families arrived, driving away the original roman community and settling here. After some years of peregrination, roman people, helped by benedictine friars, decided to build a new village, where today is the old part of the city; they called it first, “Fara benedicti” and then, “Fossa Caesa”. With the arriving of the benedictine friar Martino of Montecassino, the ancient heathen temple dedicated to Venere “Conciliatrice” was abandoned and, in this place, a cell with a chapel were built. From this moment, common people and friars created a community and started to plant fruit trees and vineyards; they developed fishing and trading and deforested the surrounding grounds. “Fossa Caesa” became a definitive titling and, with the help of Longobardi people, they built the first Christian church, dedicated to San Michele Arcangelo (St. Michael Archangel).
In the middle Ages the inhabited centre was encircled by walls and gifted of a door. In 1190 the guardian tower was built, but, in 1290, changed in bell tower for the new church of San Donato martyr. Some people believe that, in that period, even a group of soldiers coming from Fossa Caesa, decided to participate to the Crusades.
During those years, thanks to the marquise Trasmondo II and to the abbot Odorisio II, Benedictine monks built the huge monastery can we see still today. The Abbey became a very important cultural centre and, thanks to the several bestowals of the nobles, it encouraged the spreading of art. In the Abbey there were schools of theology, philosophy, Latin, art of speaking, medicine, law. Properties of the Abbey were widespread (from the town of Ravenna, in the north of Italy to Benevento, in the south part); it was the biggest feud in the south part of Italy and a lot of important characters, such as abbots, cardinals, bishops, saints, painters, sculptors, architects, scientists, philosophers, theologians, scribes, decided to visit and stayed in the Abbey.
After Longobardi people, even Normans, Svevi and Angioini decided to occupy Fossa Caesa; the name changed in Fossaceca and the local population had to bear the abuses of the new settlers. In 1447 in Fossaceca there were 126 families, about 600 inhabitants, but the earthquake of 1456 reduced the population in only 12 families. Years later, a lot of families coming from dalmatian coast moved to Fossaceca and the population could increase again.
In the sixteenth century the old inhabited centre got the administrative independence, the titling of “University” (Municipality) and the first municipal building.
In 1600 Fossaceca knew an extraordinary growth, both economically and civil and the most important local families, such as Contini, Rotondo, Polidoro, Antonacci, Sgrignuoli, Polsoni, Romanelli, Paolucci, Savelli, Nicolucci, built their beautiful palaces.
This dynamism continued even in 1700 and a lot of activities increased their importance, such as trading, farming, craftsmanship, medicine and notary. During this century, the rich and high cultured bourgeois class led the population and Fossaceca became larger than ever; a new part was built, the so called “Borgo”, beyond the ancient walls of the original core.
In the last years of the nineteenth century Fossaceca got the denomination of “Terra Regia” (Regal Land), because it was part of the Regal Court of Naples. In the same years, were established the Municipality and the National Guard, even if the revolutionary movements brought to episodes of violence. Only with the Restoration, in 1815, Fossaceca could come back to normality. In 1861, Fossaceca choose with popular vote to be part of the new unified Italy and, the following year, thanks to an act of King Vittorio Emanuele II, got the definitive denomination of Fossacesia. In 1864 the King inaugurated the Adriatic railway and all the estates of the Abbey were sold and bought by local rich families, like Mayer, Contini e Marcantonio. In the following years, Fossacesia instituted the Worker Society, with a library dedicated to Margherita of Savoia, and the first bank opened, the Cooperative Bank of Fossacesia.
A lot of young people of Fossacesia took part to the two World Wars. In 1943, German Army built the “Gustav Line”, just near Fossacesia, in order to prevent to the allies to cross the Sangro River. The most part of the city was bombed and the population forced to leave it; when they could come back, Fossacesia looked like a ghost town. About 100 civil victims died because of bombs and german mines. For this reason, with an official act of the 18th of June 2002, Chief of Italian Republic, Carlo Azeglio Ciampi, gave to Fossacesia the silver medal for the civil value during an important celebration enjoyed by all citizens, in December 2003.