Meanwhile, ever since the 25th of March, Forde's batteries had maintained a hot fire; and, though the damage done to the works by day had been regularly repaired by the besieged at night, three of the bastions had been sufficiently ruined to give foothold to a storming party. But now the weather changed, and on the 5th of April the southern monsoon broke with a flood of rain that soaked the morass around the fort to its deepest. On the morrow the storm ceased, but the day was ushered in by the gloomiest of tidings for Forde. Salabad Jung was advancing from the Kistnah, and du Rocher was on the point of junction with him. Finally, on the same evening, the artillery-officers reported that but two days ammunition was left for the batteries. Here, therefore, was the climax. Before Forde was a fortress with a garrison of greater strength than his own army; behind him was a force which outnumbered his own by more than ten to one; his communications were cut, and his ammunition and his funds were exhausted. It was open to him to embark and retire ignominiously by sea, or to stake all on a single desperate venture. He chose the bolder course and resolved to storm the fort.

During the progress of the siege it had been remarked that at the south-western corner of the fort, adjoining the sound, no ditch had been constructed; the ground without being a mere waste of mire, which might well be accounted a more difficult obstacle than any ditch. Natives, however, had more than once been seen traversing this quagmire; and Captains Yorke and Knox on making trial of it found it to be stiff and heavy indeed, but not more than knee-deep. This, therefore, was a point at which at least a false attack could be made, and Forde resolved to take advantage of it. Another point at which a feint might be directed was the ravelin outside the main gate. The true attack must of necessity be delivered against the front which had been damaged by the batteries; and the north-east bastion, known as the Chameleon, was the place selected. The necessary dispositions were quickly settled. The Rajah's troops were some of them to guard the camp, and the rest to make a demonstration against the ravelin. Captain Knox with seven hundred Sepoys was to conduct the feint attack upon the south-west angle, and the remainder of the troops were detailed for the true assault on the Chameleon bastion. The Europeans, who numbered but three hundred and forty-six, including the gunners, and thirty sailors borrowed from the ships, were told off into two divisions, the first under Captain Callendar, the second under Captain Yorke; while of the seven hundred remaining Sepoys part formed a third division under Captain Macleane, and the remainder a reserve under Forde himself. It was ordered that both the true and false attacks should begin simultaneously at midnight, when the tide would be at ebb and no more than three feet of water in the ditch; and the last stroke of the gongs within the fort was to be the signal for the storming parties to advance.

All through daylight of the 7th of April the British batteries maintained a fierce fire, playing impartially upon the three bastions of the eastern front. At length night came to silence the guns, and at ten o'clock the troops fell in for the assault. Knox having the longer distance to traverse was the first to move off, and his column presently disappeared into the darkness. The minutes flew by, and the time came for the advance of the European troops; but Captain Callendar, the leader of the first division, was not to be found. There was anxious enquiry and search, but the missing officer could not be discovered; and at length, after a precious half-hour had been lost, Captain Fischer took his place and the column marched off without him. The men were still struggling through the morass towards the Chameleon bastion when the sound of firing told them that Knox, punctual to a second, had opened his false attack. Quickening their speed as best they might, they plunged heavily on, knee-deep in mire over the swamp, waist-deep in mud and water through the ditch; when, just as Fischer's column reached the palisade, a sharp fire from the breach and from the bastions on either hand showed that they were discovered. All the more eagerly Fischer's men hewed and hacked at the palisade; while Yorke's division engaged the St. John's bastion to his left and Macleane the Small-gate bastion to his right. The men fell fast, but presently the palisades were cleared away, and the first division swarming up the breach swept the French out of the Chameleon bastion. Fischer halted for the arrival of Yorke with the second division, and then the two officers parted, Fischer to the right to clear the northern, and Yorke to the left to clear the eastern face of the fort.

Finding a field-gun with its ammunition in the Chameleon bastion, Yorke at once trained it along the rampart to southward, and was preparing to follow in the same direction himself, when he observed a party of French Sepoys advancing between the rampart and the buildings of the town to reinforce the Chameleon bastion. Instantly he ran down, and seizing the officer at their head bade them lay down their arms and surrender. Startled beyond all thought of resistance they obeyed, and were at once sent back to the captured bastion; while Yorke, taking the way by which they had advanced, pressed on against the St. John's bastion. The French guard, which had sought shelter within the angles from the raking fire of Yorke's field-gun, fired upon him and struck down not a few of his men, but surrendered immediately afterwards. They too were sent back to the Chameleon bastion, where the Sepoys took charge of them; and Yorke pursued his way to the next bastion to southward, named the Dutch bastion, where the same scene was repeated and a fresh consignment of prisoners was sent back to the custody of the Sepoys. The François bastion, the most southerly of all, alone remained untaken, and Yorke was eager to prosecute his success; but now the men hung back. The division had been not a little thinned by previous losses and by the detachment of guards for prisoners and for the captured bastions; and the handful of men that remained with the Captain began to wonder where such work was going to end. By threats and exhortations Yorke after a time induced them to follow him; but while passing an expense-magazine a little way beyond the Dutch bastion, one of the men caught sight of powder-barrels within it and cried out "A mine, a mine." Immediately every man rushed back in panic to the Chameleon bastion; and Yorke was left alone, with his black drummers by his side vainly beating the Grenadiers' March. Fortunately the guards in the captured bastions stood fast; and Yorke returning to the fugitives, who were on the point of leaving the fort, stopped the panic by threatening death to the first man who attempted to run. Rallying thirty-six men he went back to complete his work; but the delay had given the French in the François bastion time to train a gun upon the line of his advance. Waiting until his party was come within close range they fired, killed sixteen of them outright and wounded several more, including Yorke himself, who was brought to the ground with a ball in each thigh. The survivors picked him up and carried him off; but with his fall the attack in that quarter came, for the time, to an end.

Fischer meanwhile had been even more successful on the northern front. He cleared the two first bastions without difficulty, and on reaching the third, by the causeway, seized the gate and cut off the troops in the ravelin from the fort. Captain Callendar, the missing officer, suddenly appeared, no man knew from whence, in the middle of the affair, but was instantly shot dead; and Fischer was still pushing on, when he received orders from Forde to halt. Conflans throughout the attack had remained by the south front of the fort, quite at his wits' end, and adding to the general confusion by a succession of contradictory orders. Knox's attack distracted him on one side, the Rajah's troops made an unearthly din by the ravelin, and the true assault on the eastern front fairly broke his spirits down. At the very moment when Yorke's men were returning discomfited from the François bastion, he sent a messenger to Forde, offering to surrender on honourable terms. Forde was far too shrewd to betray his own weakness. He replied that he could hear of nothing but surrender at discretion; and Conflans, concluding his position to be hopeless, acceded. Five hundred Europeans and two thousand French Sepoys laid down their arms, and the British were masters of Masulipatam.

So ended this daring and marvellous adventure, with the loss to the British of but eighty-six Europeans and two hundred Sepoys killed and wounded. Salabad Jung was within fifteen miles, and du Rocher even nearer at the time of the assault; but the victory was sufficient to paralyse them also. The Viceroy quickly consented to open negotiations, and though he haggled, after the manner of his race, for a whole month, finally concluded a treaty whereby he granted to the British eighty miles of the coast, and engaged himself not only never to entertain French troops again, but even to compel such as remained to evacuate the Sirkars. Thus not only was the district secured, but French influence was displaced in favour of British at the court of Hyderabad. Such were the prizes gained by the will, resource, and resolution of one man, who had strength to rend the toils that fate had woven about him just when they seemed to have closed upon him for ever.