Complex sentence: Perdiccas immediately broke the treaty and marched to Potidaea, while the Athenians were eventually victorious, the battle (along with the Battle of Sybota) directly led to the Peloponnesian War.
Split into simpler sentences: Perdiccas immediately broke the treaty and marched to Potidaea. While the Athenians were eventually victorious, the battle (along with the Battle of Sybota) directly led to the Peloponnesian War.