As part of their plan to take overafter the British withdrawal from the country, and in order to ethnic cleanse the country from its population, the Jewish military groups adopted plan C (Gimel) by the end of 1946 followed by plan D (Dalet) few months later.
While plan "C" called for the assassination of the Palestinian political leadership, political activists and senior state officials, damaging transportation and sources of livelihoods, etc. Plan "D" called for the Palestinians systematic and total expulsion from their homeland- ethnic cleansing.
During the clashes between the Palestinian inhabitants and the Jewish militias formed by new comers, mainly from Europe, Deir Yassin has in fact reached to a non-aggression pact with the Hagana in Jerusalem (Hagana was the largest Jewish militia), however it was doomed to be wipe out due to its proximity to West Jerusalem. Accordingly, the Hagana decided to send other gangs to do the needful: Irgun and Stern terrorist troops, to release themselves from any accountability.
The incident took place on the 9th. of April 1948 when the Jewish troops occupied the village and started to attack the village houses heavily with machine guns. After killing many of the villagers, the remaining men, women and children were gathered and killed in cold blood after being abused and some women were raped before killed. Thirty babies were found among the slaughtered civilians. Some sources put the total number of victims of Deir Yassin massacre as 170 villagers.