The "irredentisti" are Italian political nationalists who consider declared themselves Italian patriots during the mid 19th to early 20th century. Their goal was to unify Italy as one whole nation, and to take back the formerly Italian territories that were now a property of Austria, and of the triple alliance that Italy had formed in 1882 with Germany and Austria-Hungary. Some of these territories included Malta, Corsica, Trieste, and Istria, among others.
Istria is a small country located in the eponymous Istrian peninsula that is mainly Croatian. However, Istria itself falls right on the Italian side. This being said, the history of Italian irredentism in Istria begins with the triple alliance against France in 1882, whose second article reads,
In case Italy, without direct provocation on her part, should be attacked by France for any reason whatsoever, the two other Contracting Parties shall be bound to lend help and assistance with all their forces to the Party attacked. This same obligation shall devolve upon Italy in case of any aggression without direct provocation by France against Germany.
This group of patriots was the inciting force behind the entrance of Italy into WWI. It was also the group that, after the War, regained the Istrian peninsula, accomplishing their ultimate goal.
Today, Istra is a great "kept secret" destination with a culture so rich in diversity that the signs in the streets denote Italian and Croatian. The Adriatic surrounding the peninsula and the combination of ethnicities make Istria a wonderful and, understandably so, sought-after place. For more information on Istria as a destination you may visit: http://visit-istria.com/whereisistria.html