Mir Jafar's signature to the treaty was received on June 12th, and Clive's force at once advanced. On that day all the troops quartered at Calcutta, together with one hundred fifty sailors from the fleet, crossed over to Chandernagor, where they joined the remainder of the force already quartered at the latter place. The Europeans, including the artillery, were sent up the river in two hundred boats, the Sepoys marching by land. On June 13th Clive despatched to the Nawab a letter which was practically a declaration of war. It arraigned the Nawab for his breach of treaty, and informed him that Clive had determined, with the approbation of all who were charged with the company's affairs, to proceed immediately to Kasimbazar, and to submit the dispute with the Nawab to the arbitration of Mir Jafar, Raja Dulab Ram, Jaggat Seth, and "others of your highness' great men." "If these," he wrote, "decide that I have deviated from the treaty, then I swear to give up all further claims upon your highness; but if it should appear that your highness has broken faith, then I shall demand satisfaction for all the losses sustained by the English, and all the charges of the army and navy." The letter ended with an intimation that as the rains were at hand, and it would take many days to receive an answer, the writer would "wait upon the Nawab at his capital to receive satisfaction." The attitude which Clive adopted was bold and defiant, but, for all that, Clive was by no means free from anxiety. It was not at all certain that Mir Jafar would adhere to his agreement. He was to have joined Clive at Katwa with a friendly force, but instead of doing so he merely sent Clive a letter promising to join him on the field of battle. On the 14th Clive's force reached Kalna, where it was joined by Watts, who had escaped from Murshidabad on the previous day. On the 17th they captured Katwa, with its fortress, after a slight resistance, and found the place well stocked with grain. On the 19th, while they halted at Katwa, the monsoon rains set in, and the troops, who were lodged in tents, had to take shelter in huts and small houses. On the same day Clive, whose anxiety continued to be very great, addressed the following letter to the committee at Calcutta:
"I feel the greatest anxiety at the little intelligence I receive from Mir Jafar, and if he is not treacherous, his sang froid or want of strength will, I fear, overset the expedition. I am trying a last effort by means of a Brahmin to prevail upon him to march out and join us. I have appointed Plassey as the place of rendezvous, and have told him at the same time that unless he gives this or some other sufficient proof of the sincerity of his intentions I will not cross the river. This, I hope, will meet with your approbation. I shall act with such caution as not to risk the loss of our forces; and whilst we have them, we may always have it in our power to bring about a revolution, though the present should not succeed. They say there is a considerable quantity of grain in and about the place. If we collect eight or ten thousand maunds" (eight or ten hundred thousand pounds), "we may maintain our situation during the rains, which will greatly distress the Nawab, and either reduce him to terms which may be depended upon, or give us time to bring in the Birbhum Raja, the Mahrattas, or Ghazi ud din. I desire you will give your sentiments freely how you think I should act if Mir Jafar can give us no assistance."
The situation was certainly a very alarming one. Clive had only 3200 men to oppose what proved to be an army of 50,000. He had no cavalry, and only a few guns, while the enemy had a large artillery force. In the circumstances, it is perhaps hardly to be wondered at that Clive should desire to share the responsibility. This he did, for what proved to be the first and last time in his life, by holding a council of war, to which he propounded the following question: "Whether, in our present situation, without assistance, and on our own bottom, it would be prudent to attack the Nawab, or whether we should wait till joined by some country power." Of the sixteen members of the council, nine, including Clive, voted for delay, and seven, including Eyre Coote, were for an immediate attack. But Clive did not adhere to his original vote. After the council had risen, he withdrew to a clump of trees, and having passed an hour in thinking over all the arguments for and against delay, he determined to move forward at once. Meeting Eyre Coote on his way back to camp, he told him he had changed his mind, and intended to march the next morning. Accordingly, in the early morning of June 22d, the force marched down the bank of the Bhagirathi, and crossed the river the same afternoon without meeting with any opposition. There still remained fifteen miles to be traversed in order to reach Plassey. Clive's force, after struggling through mud and water in a continued torrent of rain, did not arrive at the village until one o'clock on the morning of the 23d. Clive had heard from Mir Jafar that the Nawab's army would halt at Mankarah, a place some miles short of Plassey; but the Nawab had changed his plans, and reached Plassey twelve hours before Clive. Thus, on his arrival, Clive found that the enemy were close at hand. He spent the remainder of the night making his dispositions, while his troops bivouacked in an extensive mango-grove on ground already soaked by the rain, which was still falling. The mango-grove was 800 yards in length and 300 in breadth, and was surrounded by a bank and a ditch. About fifty yards beyond it stood a hunting-box belonging to the Nawab of Oude. Of this Clive at once took possession. The grove was little more than a mile from the Nawab's encampment. The force under Clive, as stated, did no exceed 3200 men, of whom 900 were English, 200 were Eurasians, and 2100 native Sepoys. There was a small artillery train, composed of eight six-pounders and two small howitzers. The Nawab's army, so far as numerical strength was concerned, was enormously superior to Clive's force. It consisted of 35,000 infantry—for the most part imperfectly trained and undisciplined—and 15,000 cavalry well mounted and well armed. He had 53 pieces of artillery, most of them of heavy calibre, and with them 40 or 50 Frenchmen commanded by M. St. Frais, who had been a member of the French council at Chandernagor. His army occupied a strongly intrenched position. His right rested on the river, while his left stretched out into the open plain.
The following is a brief description of the battle, taken from Clive's journal of military proceedings:
"At daybreak we discovered the Nawab's army at the distance of about three miles in full march towards us, upon which the whole were ordered under arms, being in two battalions. The Europeans were told off in four grand divisions, the artillery distributed between them, and the Sepoys on the right and left of the whole.
"Our situation was very advantageous, being in a grove surrounded by high mud-banks. Our right and front were entirely covered by those mud-banks, our left by Placis' house and the river, our rear by the grove and a large village. The enemy approached apace, covered a fine extensive plain in front of us as far as the eye could discern from right to left, and consisted, as we have since learned, of 15,000 horse and 35,000 foot, with more than 40 pieces of cannon, from thirty-two to nine pounders. They began to cannonade from this heavy artillery, which, though well pointed, could do little execution, our people being lodged under the banks. We could not hope to succeed in an attempt on their cannon, as they were planted almost round, and at a considerable distance both from us and each other. We therefore remained quiet in front, in hopes of a successful attack on their camp at night. At 300 yards from the bank under which we were posted was a pool of water with high banks all round it, and was apparently a post of strength. This the enemy presently took possession of, and would have galled us much from thence but for our advantageous position, with some cannon managed by 50 Frenchmen. This heavy artillery continued to play very briskly on the grove.
"As their army, exclusive of a few advanced parties, were drawn up at too great a distance for our short sixes to reach them, one field-piece with a howitzer was advanced 200 yards in front, and we could see that they played with great success amongst those that were of the first rank, by which the whole army was dispirited and thrown into confusion.
"A large body of their horse starting out on our right, and as by that movement we supposed they intended an attempt on the advanced field-piece and howitzer, they were both ordered back.
"About eleven o'clock a very heavy shower of rain came on, and we imagined the horse would now, if ever, have attacked in hopes of breaking us, as they might have thought we could not then make use of our firelocks; but their ignorance or the brisk firing of our artillery prevented them from attempting it.
"At noon, a report being made that a party of horse had attacked and taken our boats, the pickets were ordered, but, the account proving false, they were countermanded.