He returned to Greece, and survived the German occupation during World War II. Between 1942 and 1944, Kyriakides was part of the Greek resistance. With the Greek Civil War raging, he returned to win the 1946 Boston Marathon. In order to get there, he had to sell his furniture, enabling him to buy a single ticket. According to a newspaper report, he was running with Johnny Kelley near the end, when an old man shouted from the crowd, 'For Greece, for your children!', inspiring him to pull away and win the race in 2:29:27, the fastest marathon time of 1946, and 14 minutes faster than his previous best time. According to "Life" magazine, he shouted 'For Greece' as he crossed the finish line. He begged America for its help—and Americans responded. When he returned to Greece, he arrived with 25,000 tons of supplies in American aid, including $250,000 in cash. Over one million Greeks from all over the country lined the streets of Athens to greet him. Johnny Kelley purchased the shoes that Stelios Kyriakides used in his victory.