was sacked by German troops and the Battle of Le Cateau was fought by the BEF and the 1st Army. Longwy was surrendered by its garrison and next day British Marines and a party of the Royal Naval Air Service (RNAS) landed at Ostend; Lille and Mezières were occupied by German troops. Arras was occupied on 27 August and a French counter-offensive began at the Battle of St Quentin (1914) (Battle of Guise On 29 August the Fifth Army counter-attacked the 2nd Army south of the Oise, from Vervins to Mont Dorigny and west of the river from Mont Dorigny to Moy towards St Quentin on the Somme, while the British held the line of the Oise west of La Fère. Laon, La Fère, and Roye were captured by German troops on 30 August and Amiens the next day. On 1 September Craonne and Soissons were captured and on 5 September the BEF ended its retreat from Mons, German troops reached Claye, from Paris, Reims was captured, German forces withdrew from Lille and the First Battle of the Marne (Battle of the Ourcq) began, marking the end of the Great Retreat of the western flank of the Franco-British armies. By 4 September the First and Second armies had slowed the advance of the 7th and 6th armies west of St Dié and east of Nancy, from where the Second Army had withdrawn its left flank, to face north between Nancy and Toul. A gap between the left of the Second Army and the right of the Third Army at Verdun, which faced north-west, on a line towards Revigny against the 5th Army advance, west of the Meuse between Varennes and St Ménéhould. The Fourth Army had withdrawn to Sermaize, west to the Marne at Vitry le François and then across the river to Sompons, against the 4th Army, which had advanced from Rethel, to Suippes and the west of Chalons. The new Ninth Army held a line from Mailly against the 3rd Army, which had advanced from Mézières, over the Vesle and the Marne west of Chalons. The 2nd Army had advanced from Marle on the Serre, across the Aisne and the Vesle, between Reims and Fismes to Montmort, north of the junction of the Ninth and Fifth armies at Sezanne. The Fifth Army and the BEF had withdrawn south of the Oise, Serre, Aisne and Ourq, pursued by the