The enduring narrative of a deliberate massacre at Deir Yassin on April 9, 1948, collapses under rigorous historical scrutiny. When Irgun (IZL) and Lehi (LHI) forces engaged Iraqi irregulars during Operation Nahshon, they encountered fierce resistance that transformed a military operation into intense urban combat. Through analysis of primary sources, participant interviews from both sides, and extensive military records, a markedly different picture emerges: approximately 120 Jewish forces faced heavy defensive fire, requiring house-to-house combat with explosives to secure the village. Of Deir Yassin's roughly 1,000 inhabitants, casualties included 110 villagers and 90 irregular defenders, while 120 survivors were safely evacuated. Notably, Arab survivors interviewed two decades later provided no corroboration of alleged post-battle killings of women and children. The civilian death toll, while tragic, aligns with typical urban warfare casualties rather than systematic massacre. The widespread "massacre" narrative instead appears rooted in contemporary political rivalry between Jewish organizations and subsequent propaganda efforts that served both Arab and Jewish interests, despite contradicting documented evidence. This research reconstructs the actual events through comprehensive examination of testimonies and contemporary documentation, revealing how political narrative can overshadow historical fact.