Final answer:
Italy successfully invaded Greece with the aid of German forces during World War II.
Step-by-step explanation:
The region that Italy successfully invaded with the aid of German forces was Greece. During World War II, Italy, under the leadership of Benito Mussolini, launched an invasion of Greece in 1940. However, the Greek army, with the support of Allied forces, managed to repel the Italian invasion. Germany then came to Italy's aid and launched its own invasion of Greece, ultimately resulting in the occupation of the country by German forces.
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