After the Italian unification and during the first half of the XIX Century, various government decrees ordered the change of the name of some comuni to avoid confusion between homonymous places, in some cases and additional place name for those towns with the same name (e.g. about 13 Italian comuni are called Acquaviva) in other cases, a little variation was added to the name.
The fascism imposed the Italianization of the names of those towns whose name were more similar to a French or German name rather than to an Italian one. After 1945 these places recovered their original names.
See: List of Italian city name changes
Towns which disappeared: called the comuni soppressi
There are some comuni which as time went by, were absorbed by a more important town. This happens as a consequence of urban development or the construction of roads which have made the communication and transfer of people easier. There may have been cases of one town being divided into two new ones.
But it was mainly after the First World War and during the Fascist era whose intention was to reduce the number of towns that many small comuni merged to become a new one. A series of decrees issued between 1923 and 1927 considerably reduced the number of comuni. Only in 1927 800 small comuni were suppressed without any criteria or previous information to their inhabitants. Only in 1934 a single criterion was applied which stipulated a minimum of 3,000 inhabitants to create a new comune.
This process was done in two ways: several comuni were unified into a new comune or a small comune was annexed to another neighbouring comune. There were also many separations into frazioni which became part of another comune.
After 1945 many comuni returned to their original status and others continued being merged.
See: List of Italian Towns