The Peloponnesian War was a war between Athens and Sparta. The Athens wanted to defend their leadership, but Sparta was jealous of the Athenian power. There was a plague in 430 B.C. that spread throughout Athens, killing one- third of the Athenian population. Sparta and Athens fought on and off, but Athens soon decides to invade Sicily, an island in Italy. The Athenians attacked Syracuse, one of Sparta's allies, hoping that Sparta would come to them. Sparta, however, is victorious in saving Syracuse. There is a constant battle in Athens, but they end up surrendering to Sparta, losing their power and wealth over the Delian League. They do not lose their independence.