On April 16-17, 1918, Foch's men carried out a successful attack northwest of Soissons in the Autrèches region, and operating on a three-mile front smashed through enemy positions to the depth of a mile. They won in this advance the important plateau to the north of the village of Autrèches, which gave them command of the country extending northward, south of the Oise River. Further local actions at other points on the front greatly strengthened the grip of the Allies on the approaches to Roye to the west, north, and south. The Germans in that region maintained an incessant artillery fire, but the only effect it had was to delay for a time the Allies' advance. The French were now within a mile of Roye on two sides. British troops under Marshal Haig meanwhile were not idle. Good progress was made on the 17th to the north of Proyart, just south of the Somme. Farther to the south, troops operating north of Lihons, which lies about two miles to the west of Chaulnes, pushed their line forward to the depth of a mile. More progress was also made in the Amiens-Roye road region and to the north of the Ancre River. West of Armentières British troops drove the Germans back on a front of four miles between Bailleul and Vieux Berquin in the Lys sector. They also captured the village of Outersteene, a mile east of Merris and took 400 prisoners. The German positions around Roye continued to be threatened by the British pressure, and on August 18, 1918, Marshal Haig's men pushed their line forward to the north of that place between Chilly and Fransart. To the south of the Avre River the French, as they fought their way forward, captured over 400 Germans, overcoming some important enemy strongholds. From the positions captured by the French north of the Aisne River the Allies could now dominate the German batteries of big guns at Chavigny and Juvigny, north of Soissons. These batteries were formidable, commanding not only the city of Soissons, but a wide region around. The Allies were now able to exert such pressure on the Germans here that they must soon be forced to retire and the city of Soissons would be relieved of the danger of bombardment. Allied operations on two widely separated fronts--the British on the north of the Lys salient, and the French between the Aisne and the Oise--had increased the difficulties of the Germans in these areas. Lassigny was seriously threatened by the capture of Fresmières (on the Roye highroad two and a half miles to the north) by the advance of Foch's troops to the western outskirts of the town, and the occupation of the Thiescourt Wood.