After Ben-Yosef's execution, the Irgun launched a series of operations against the Arabs. The central acts were the explosions in the Arab markets of Haifa and Jerusalem. On July 6, 1938, a member of the Irgun, disguised as an Arab porter, went into the Arab market in Haifa, placed a large parcel beside one of the barrows in the center of the market and left. Shortly afterwards there was a heavy explosion, which killed 21 Arabs and injured more than 50. A week later a similar incident took place in Jerusalem. A member of the Irgun concealed an electric mine in the Arab market in the Old City. It exploded shortly after the end of the prayer service in the mosque, when a large crowd had emerged onto the street. Eight Arabs were killed and more than 30 injured.
On July 26, 1938, Yaakov Raz was sent to the Old City of Jerusalem disguised as an Arab and carrying a basket of vegetables in which a mine was concealed. His commanding officers, who had planned the operation far in advance, did not heed the fact that the Arabs had proclaimed a general strike that day in protest against the Irgun's incessant attacks. When Raz placed the basket beside one of the stores whose doors were barred, he aroused the suspicion of the Arab bystanders. His basket was overturned and when the mine was found, Raz was repeatedly stabbed. The Arabs then fled, leaving him for dead. Yaakov Raz was severely injured, and was taken by the police to the government hospital. Despite his serious condition, he was interrogated by the British Intelligence, the CID (Criminal Investigation Department), throughout his hospital stay. For two weeks he fought for his life. When he felt his strength waning, and feared he would not be able to withstand further interrogation and was liable to betray secret information, he tore off his bandages and died of blood loss.
Yaakov Raz was the first member of the Irgun to die as a result of an operation. The heroism he displayed, and particularly the manner of his death, made him a symbol and inspiration for generations of young Irgun members.