The origins of Campobasso are disputed.
According to the most widely held theory, the city was founded by the Lombards before the 8th century as a fortified camp on the slope of the hill where the castle stands.
 The original name was Campus vassorum, suggesting that the city was the seat of the vassals of the duke of Spoleto.

After the Norman conquest of Southern Italy, Campobasso lost its importance as a defensive stronghold, but became a significant trading and administration centre.

From 1330 to 1745 the city was ruled by the Monforte-Gambatesa family, who built the castle and established a mint.
Later it came under the control of the Di Capua, Gonzaga, Vitagliano, Carafa and Romano families.

The original old town of Campobasso contains the Castello Monforte, although in 1732 the inhabitants built a new town on a lower-level plain.

In 1763 the citizens abandoned the old city and settled in the lower valley.
The current city was expanded in 1814 by the king of Naples Joachim Murat, and lies on the Campo Basso ("Low field").

Campobasso was the scene of heavy fighting during the Second World War.
In the months of October and November 1943 a battle between the German and the Canadian troops for possession of the city caused the destruction of many public buildings, including the City Hall and the archives held there.
 Thirty eight civilians were killed in the action, including the bishop of the diocese, Bishop Secondo Bologna, and an unknown number of people were injured in the intensive bombardment.
 The occupation by the Canadian troops, and the administrative and political control resulting, had such an impact on the town that it became known as "Canada Town" or "Maple Leaf City".

In 1995 the city was awarded the Bronze Medal for Civil Valour in recognition of the hard work done in clearing the region of dangerous unexploded warheads, a task that lasted well into 1948.
The origins of Campobasso are disputed. According to the most widely held theory, the city was founded by the Lombards before the 8th century as a fortified camp on the slope of the hill where the castle stands.  The original name was Campus vassorum, suggesting that the city was the seat of the vassals of the duke of Spoleto.
After the Norman conquest of Southern Italy, Campobasso lost its importance as a defensive stronghold, but became a significant trading and administration centre.
From 1330 to 1745 the city was ruled by the Monforte-Gambatesa family, who built the castle and established a mint. Later it came under the control of the Di Capua, Gonzaga, Vitagliano, Carafa and Romano families.
The original old town of Campobasso contains the Castello Monforte, although in 1732 the inhabitants built a new town on a lower-level plain.
In 1763 the citizens abandoned the old city and settled in the lower valley. The current city was expanded in 1814 by the king of Naples Joachim Murat, and lies on the Campo Basso ("Low field").
Campobasso was the scene of heavy fighting during the Second World War. In the months of October and November 1943 a battle between the German and the Canadian troops for possession of the city caused the destruction of many public buildings, including the City Hall and the archives held there.  Thirty eight civilians were killed in the action, including the bishop of the diocese, Bishop Secondo Bologna, and an unknown number of people were injured in the intensive bombardment.  The occupation by the Canadian troops, and the administrative and political control resulting, had such an impact on the town that it became known as "Canada Town" or "Maple Leaf City".
In 1995 the city was awarded the Bronze Medal for Civil Valour in recognition of the hard work done in clearing the region of dangerous unexploded warheads, a task that lasted well into 1948.
Campobasso