rest of the British Army) had cleaned up the whole of the area to the north-west of Ghevgheli and to the north-east of the Vardar on the Gradetz mountains. On the 29th it occupied Radovista, and effected a junction with the Serbs. [Illustration: GRÆCO-BULGARIAN FRONTIER. To face p. 242. ] The British now continued their pursuit of the enemy in their desperate retreat towards Strumitza, and soon occupied the whole of the area to the west and north of Lake Doiran. On the 25th the troops of the XVI Corps advanced to the right and left of the Doiran-Strumitza road, and penetrated into Bulgaria by the Kosturino pass; on the 26th they occupied Strumitza itself.[43] These were the first Allied detachments to penetrate into enemy territory in the Balkans; actually the first to enter were the Derbyshire Yeomanry. The XII Corps had, in the meanwhile, pushed towards the right of the XVIth, and on the 25th commenced the attack on the Beles to the east and the right. On the same day General Milne transferred his G.H.Q. from Salonica to Janesh in order to be nearer the scene of operations. On the 26th, detachments of the British 22nd and 20th Divisions and the Cretan Division, and of the 2nd bis Zouaves regiment attacked the Bulgarians entrenched on the Beles, that vast mountain wall from 1,100 m. to 1,600 m. high, which for two years has seemed an absolutely impregnable barrier. The enemy offered but slight resistance, because they were already beaten, and the heights were occupied one after the other. On the 28th a regiment of the Cretan Division pushed along the ridge from west to east, another, together with the British 228th Brigade, advanced along the valley below towards Lake Butkova, and a third column of the XVI Corps followed the parallel valley to the north, down the course of the River Strumitza. The object of this triple advance was to reach the Struma towards the Rupel and Kresna gorges, and thus cut off the retreat of the forces of the II Army, which had remained until then on the lower Struma.