The italian Frogmen
For more than 1000 years, while Rome was the center of the Roman Empire, Italy's extended coastline remained practically impenetrable to foreign intruders. With the fall of the Empire, however, just about every, foreign power laid siege to the Italian boot-like peninsula. Its territory runs north and south, from the Alps which run east to west, to the Apennines which run north to south all the way down to Sicily. Italy's more than 2000 miles of prolonged shorelines surrounds a territory ravished by marauders and foreign armies on a regular basis until around 1850. In a movement called Risorgirnento, Italy was united into a nation by Giuseppe Garibaldi. With barely 1000 red-shirted troops, he invaded Sicily and fought his way northward where he expelled the Austrians.
Nevertheless, as a new nation, Italy was never free from threats of invasion especially from land-locked Austria which was in need to gain more and better access to the Mediterranean Sea. With its Port of Pala east of Venice, however, Austria's mighty naval force was able to dominate the Adriatic, and to virtually contain Italy--to the north with its land forces, and along Italy's entire eastern coast all the way down to Sicily with its naval forces.