By the time Tukhachevsky's forces reached the Bug River on July 22–23, Polish resistance began to harden.
The French, who had always maintained a large, well-informed military mission in Poland, felt that Pilsudski was somehow uninterested in the military disaster.
They were convinced that he was more concerned with maintaining himself as head of state than waging war:he had entrusted the conduct of the long retreat to the young director of the Polish Third Bureau (the equivalent of the Director of Operations military), a 28-year-old officer named Stackiewicz. On this occasion, however, Stackiewicz had done a fine job of bringing the relatively weak Polish army back to the Bug.
The French were unimpressed and, supported by the British, they did everything they could to get the Poles to accept General Weygand as the de facto commander-in-chief of their army.
Despite refusing an official rank and title in the Polish army, Weygand had repeatedly tried to get the Poles to take him on as a military adviser and allow him access to their secret reports. Wasn't he, after all, a prestigious chief of staff with a glorious past and, with the help of Radcliffe, wasn't he in a position to help the Poles save something from the sinking ?
The Poles themselves were indeed obliged to heed somewhat the Allied advice in the hope of receiving more supplies; but, not supporting any foreign reins, they endeavored to exclude Weygand from any decision having a real range.
In early August, Pisuldski began to take a closer interest in the war. He was a complex man - a romantic and a dreamer but also an unorthodox and daring soldier. Until the end of July, he had been able to believe that the Russians had attacked simply to reconquer the bordering provinces won by Poland in 1919.
On July 27, he declared to Radcliffe that the Soviets would not dare to cross the Curzon line (demarcation line proposed on July 10 by the British as the eastern border of Poland) for fear of a new Franco-British intervention.
By August it was evident not only that they had passed it but also that they saw Warsaw as a mere stage before the invasion and bolshevization of Germany. In fact, Tukhachevsky had in mind the wild idea of an offensive that would overwhelm Europe. Pilsudski woke up but judged that the disaster was too big to be repaired. Weygand insisted, on the contrary, that the Poles resist and stop the Bolsheviks along the Bug.
But, on August 1, Brest-Litovsk fell prematurely into the hands of the XVI Army and the local Communists who seized the telephone exchanges. Warsaw, 210 km away, would be the next objective.
Pilsudski understood that he could not lose the capital, which housed most of the war material and supplies.
He had to launch a counter-offensive with fresh troops - gold, these troops he did not have. Desperately seeking a solution, Pilsudski had to resign himself to accepting certain ideas of Weygand. From the moment of his arrival, Weygand had never ceased to emphasize the importance of the northern front, insisting over and over again that some of the troops who were facing Boudienny's Konarmiya be repatriated to the north.
The Poles refused to cede an inch of ground to the south, where the population was not one hundred percent Polish; they well knew, in fact, that this territory, if it were lost, would be very difficult to reconquer under the terms of any peace treaty.
But Weygand saw that war would be decided North. On August 3 he again calmly insisted on this point, which provoked a heated argument with the Polish Chief of Staff, General Rozwadowski.
He maintained that the maneuver was impossible, because the Polish army was ill-prepared, ill-trained and poorly equipped:“Let Weygand do my job; he will find the Polish army very different from the one he is used to and he will come up against more delicate problems. »
Meanwhile, Tukhachevesky was making his plans to capture Warsaw. He hoped to finally trap the elusive Polish army there and destroy it before continuing on to Germany.
On August 8, he gave his instructions. The IIP, IV' and XV' armies (74,000 men) were to operate a hook to the north (with inevitably at their head the Kavkor strong of 4,700 men), overcome the northern defenses of Warsaw and cross the lower Vistula before initiating a turning movement and encircle it.
The XVI Army (20,700 men) would march on the capital from the east, leaving only a weak flank-guard constituted by Mosyr's group of 8,000 men to provide cover along the lower Vistula. Tukhachevsky was not worried about his flank.
The Poles, he thought, were already beaten. At his request, the Soviet High Command entrusted him with control of the Konarmiya and the XII Army, detached since April 14 from the troops of Alexander I. Yegorov.
But there was no indication that Tukhachevsky intended to use the Konarmiya threat to pin down Polish forces as he stormed Warsaw. He simply continued to advance, supremely confident:the Polish army was already beaten and the Russian flank would only be exposed for a few inconsequential days.