Italy invading Greece during WW2 was the biggest fukk up because the Greeks actually resisted for 6 months and it fukked up the entire timeline. Mussolini is basically why Nazis lost the war
Winston Churchill:
"The word heroism I am afraid does not render the least of those acts of self-sacrifice of the Greeks, which were the defining factor in the victorious outcome of the common struggle of the nations, during WWII, for the human freedom and dignity. If it were not for the bravery of the Greeks and their courage, the outcome of WWII would be undetermined." (Paraphrased from one of his speeches to the British Parliament on 24 April 1941)
Joseph Vissarionovich Tzougasvili Stalin:
"I am sorry because I am getting old and I shall not live long to thank the Greek People, whose resistance decided WWII." (From a speech of his broadcast by the Moscow radio station on 31 January 1943 after the victory of Stalingrad and the capitulation of marshal Paulus)
Moscow, Radio Station to Greece:
"You fought unarmed and won, small against big. We owe you gratitude, because you gave us time to defend ourselves. As Russians and as people we thank you." (When Hitler attacked the U.S.S.R.)
Georgy Constantinovich Zhoucov 1896-1974 Marshal of the Soviet Army:
"If the Russian people managed to raise resistance at the doors of Moscow, to halt and reverse the German torrent, they owe it to the Greek People, who delayed the German divisions during the time they could bring us to our knees." (Quote from his memoirs on WWII)
Sir Harold Leofric George Alexander, British Marshal during WWII:
"It would not be an exaggeration to say that Greece upset the plans of Germany in their entirety forcing her to postpone the attack on Russia for six weeks. We wonder what would have been Soviet Union's position without Greece." (Paraphrased from a speech of his to the British parliament on 28 October 1941)
So it was Nazi Italy and their groupie actions that caused the empire to fall.....