On February 14, Ukrainian forces began another assault on Lviv. By February 20, they were able to successfully cut off the rail links between Lviv and Przemysl, leaving Lviv surrounded and the Ukrainian forces in a good position to take the city. However, a French-led mission from the Entente arrived at the Ukrainian headquarters on February 22 and demanded that the Ukrainian cease hostilities under threat of breaking all diplomatic ties between the Entente and the Ukrainian government. On February 25 the Ukrainian military suspended its offensive. The Barthélemy mission proposed a demarcation line (February 28) leaving almost 70% of the East Galician territory to Ukrainians, and Lviv with oil fields to Poland. The Ukrainians would be supplied with half of the oil production. The proposal was accepted by the Poles. The Allied demands, which included the loss of significant amount of Ukrainian-held and inhabited territory, were however deemed to excessively favor the Poles by the Ukrainians, who resumed their offensive on March 4. On March 5 Ukrainian artillery blew up the Polish forces' ammunition dump in Lviv; the resultant explosion caused a panic among Polish forces. The Ukrainians, however, failed to take advantage of this. During the time of the cease-fire, the Poles had been able to organize a relief force of 8,000–10,000 troops which by March 12 reached Przemyśl and by March 18 had driven the Ukrainian forces from the Lviv-Przemyśl railroad, permanently securing Lviv.