The Battle of Crete lasted ten days, during which Helias' brother George Doundoulakis worked as an interpreter for the joint Greek/British military headquarters.

"Monty" Woodhouse, a Special Operations Executive (SOE) agent, approached George after witnessing his competence and leadership abilities.

[1]: 278 [2] George's organization supplied key intelligence to the SOE by collaborating with Woodhouse, then with Thomas Dunbabin ("Tom"), and later, Paddy Fermor ("Mihalis").

Helias was assigned to the Heraklion Airfield, where he relayed to a nearby peanut vendor the number of Luftwaffe planes returning from Rommel's Afrika Korps in Egypt.

For their action, George and Dunbabin later were decorated by Great Britain, the former receiving the King's Medal and the latter the Distinguished Service Order.

Leigh Fermor urged Helias and George to depart immediately to the south shore of Crete through the Psiloritis Mountains and await exfiltration by the SOE.

[4]: 72  After the war, Leigh Fermor was immortalized in the British film, Ill Met by Moonlight for his role in abducting General Kreipe from Crete.

[5]) After safely arriving in Mersa Matruh, Helias, George, John ("Yanni") Androulakis[1]: 147–150, 155  and three others were transported to an SOE villa in Heliopolis, an affluent suburb of Cairo.

Prospective agents were trained inside an elaborate palace rented from Egypt's ruling monarch, King Farouk.

Helias remained embedded undercover in Salonica from April to December 1944, sending encrypted radio messages to OSS-Cairo on German activity.

Entrenched in the impassable Pelion Mountains of Thessaly, they destroyed Greece's eastern railway system and Volos' maritime link to Athens, effectively choking the German Army.

[4]: 325 Doundoulakis was employed at Grumman Aerospace Corporation for over thirty five years and group leader on many USAF and NASA projects.

[4]: 325–327 Doundoulakis patented the unique suspension system for a radio telescope used in the design for the largest of its kind at the time, the Arecibo Observatory, Puerto Rico.

[14][15][16] He worked on this project with guidance from his brother, George Doundoulakis, head of research at the General Bronze Corporation, and who had initiated this novel idea for Arecibo's suspension system.

Hurricane Maria, though wreaking havoc on Puerto Rico's electrical grid, caused only minor damage to the Arecibo Observatory.