The conflicts in the play develop from an event that is revealed through exposition. During World War II, Joe Keller ordered his partner to conceal defects in 121 plane engines their company supplied to the Air Force during World War II. As a result, 21 fighter planes that were fitted with the defective parts crashed, killing those soldiers on board.
The significance of the title is made clear in the play's conclusion when Keller finally faces the truth of his own character and assumes responsibility for his actions. As a result of his greed and deception, he has lost the respect of his son Chris, a young man of principle. Keller's son Larry, who was shamed beyond endurance by his father's reprehensible acts, committed suicide. In addition to these sons, however, Keller finally takes direct responsibility for "all my sons," the soldiers who died flying the planes sent into combat with his defective parts. As the enormity of his selfishness and greed overwhelms him, Keller kills himself in the play's conclusion.