For some time it was a mystery to the Allies as to how the Germans succeeded in bringing forward new divisions into the battle area and so often escaping the notice of the vigilant French and British observers. This the Germans accomplished by exercising the greatest precaution and cunning. In the first place the territory occupied by each German army corps was divided into two zones, the first of which might be under observation of the Allies' lookouts, and the other only from captive balloons which had a wide radius of view. According to German army orders, infantry occupying the first zone were forbidden on clear days to move in any greater number than four men together, mounted men not more than two together, and vehicles not more than two at a time, with a minimum of 300 yards between groups. In heavy, misty weather, these restrictions were relaxed and the movement of groups of forty foot soldiers, twenty cavalrymen, and ten vehicles was permitted. In the second zone it was permissible to form groups of the size allowed in the first zone, on days of poor visibility, but there must be intervals of 500 yards. It was in this manner that the Germans' military movements were often hidden from the Allies' observers. German divisions making forced marches in the night slept in the villages during the day, and were heavily punished if they showed themselves in the streets. No infantry operations were attempted by the Germans on May 1-2, 1918, but German gunners continued at regular intervals to bombard the Franco-British lines. General Pétain took advantage of the lull in the fighting to advance his lines between Hailles and Castel (south of the Avre), meeting with little opposition, capturing Hill 82 and the wood near by bordering on the river. The Germans became active again on May 3, 1918, when, after a heavy artillery barrage, they attacked British positions south of Locon (on the southern flank of the Lys salient). They were easily repulsed and made no further attempt that day to renew the attack. On May 4th, 1918, British and French troops carried out a successful operation between Locre and Dranoutre, gaining ground on a half-mile front to an average depth of 500 yards and capturing a number of prisoners. The Germans were driven from three ruined farms that were perfect strongholds, and high ground was won by the Allies near Koutkot (west of Dranoutre). All these local successes were of real value, for they strengthened the Allied defenses of the approach to Scherpenberg and Mont Rouge. May 5, 1918, was a great day for those irrepressible fighters, the Australians, who gave the Germans a bad thrashing west and southwest of Morlancourt between the Ancre and the Somme Rivers. The Australians' attack was made on a front of 2,500 yards unheralded by any preliminary bombardment, but the British guns became active after they were on their way, keeping roads and tracks under fire to prevent the enemy from bringing up supports.