The Battle of Dervenakia () was the Greek victory over the Ottoman forces on 6–8 August 1822, an important event in the Greek War of Independence.
It resulted in the defeat of a major expedition by Mahmud Dramali Pasha, intended to quell the ongoing Greek rebellion which had begun in 1821. The destruction of Dramali Pasha's forces saved the heartland of the rebellion, the Morea, and secured it for the Greeks until the arrival of Ibrahim Pasha in 1825.
Background
After the Greek victory at the Battle of Vasilika in 1821, the Ottoman army was prevented from entering Attica and the Peloponnese, and by the summer of 1822 the Ottomans were prepared for another attempt to move southwards and crush the Greek uprising. The Ottomans had assembled an army of some 20,000 men and 8,000 cavalry with ample supplies and transportation at Larissa, which was eventually entrusted to Dramali Pasha of Drama, the army was the largest seen in Greece since the last Ottoman-Venetian war. Dramali was expected to crush the Greek rebellion by advancing to Corinth, relieve the besieged garrison of Nafplion and recapture the capital of the Morea, Tripoli. While the Ottomans were now in a better position than a year earlier, the same could not be said for the Greeks who had been weakened by infighting and disagreement between their leaders, who failed to cooperate and make adequate preparations for Dramali's advance.
Start of the campaign and retaking of Corinth
In early July, Dramali set out from Zitouni (today Lamia) and found initial success. The Greeks, who were unprepared, left Dramali's army largely unassailed, and by the 17th of July Dramali had retaken Corinth, which had been abandoned by its defenders. However, Dramali decided against retaking Athens, which had fallen earlier to the Greeks on 21 June. At Corinth, Dramali held a military council to decide on future actions. Emboldened by the rapid progress and disintegration of the Greeks at the beginning of his campaign, Dramali proposed to march his entire army to Nafplio. This was met with disagreement from Yussaf Pasha and Ali Pasha, who instead proposed to strengthen their position at Corinth and to build up a strong naval force in the Saronic Gulf. Dramali rejected this plan and decided to carry out his march towards Nafplion.
Siege of Nafplion
Dramali passed through the narrow defile known as the Dervenaki (Tretos) and on 24 July reached Argos, whence the Greek government had fled. The flight of the Greek government from Argos without a shot being fired inflicted a blow to its prestige that it never recovered from as many Greeks damned their government as one of cowards. Earlier that year, the Ottomans had committed the Chios Massacre, and refugees from Chios had brought vivid tales of the murder, rape and enslavement committed on Chios to the mainland; the news of Dramali Pasha's advance created panic all over the Morea. The Maniots, who were supposed to stop the Ottomans instead robbed the refugees, leading Colonel Thomas Gordon to caustically comment that the Maniots “would have reputed it a disgrace to have gone back to their mountains as poor as they left them”. Dramali Pasha left no guards behind him in the Dervenaki and he posted no forces where other defiles exposed his flanks. He sent cavalry forward to join the Ottoman garrison at Nafplion, which at that time was on the point of capitulation. As it was, Dramali was able to seize the Greek hostages which the garrison was held there as a pledge for the safety of Muslim hostages held by the Greeks.