The ‘Thucydides Trap' is a term coined by Harvard professor Graham Allison to ostensibly describe the tensions and conflict that occur when an existing great power is confronted with a rising state. According to Allison, as the new power rises, the two are more likely to engage in violent conflict as the new power displaces the old. He cites sixteen cases of power transition since the late 15th Century, of which twelve resulted in war between the two powers. Allison also cites Thucydides, and in particular the ancient Athenian author’s conclusion that the war between Athens and Sparta, chronicled in his History of the Peloponnesian War, began "because they [the Spartans] were afraid of the further growth of Athenian power.”