The outcome of the siege however was decided many miles to the north of Baghdad near a city called Samarra where Istanbul had sent the best army it could muster under the command of the best general it had: Topal Osman Pasha. Nader arrogantly marched north to attack the Ottoman relief force instead of choosing a suitable battlefield for a defensive battle. The result was one of the most bloody engagements of Nader's campaigns with almost half the Persian army becoming 'hors de combat' with even the Ottomans losing a quarter of their army leaving a terrifying 20,000 men as casualties of the debacle.