At Singapore, 135th Field Rgt was reunited with its own 25-pounder guns, just arrived with the rest of 18th Division. 336 Battery was the last to refit, due to the casualties it had suffered, and moved into positions near Nee Song on 4 February. The regiment formed part of the Northern Area defences between the Naval Base and the causeway. 499 Battery established an OP in a water tower on the edge of the naval base, whole 344 Bty's was in a partially completed building overlooking the causeway; other forward observation officers (FOOs) were established along the water's edge. 4th (Hazara) Mountain Battery, Indian Artillery, equipped with two 6-inch howitzers, and a section of 273 Anti-Tank Bty armed with 2-pounder guns were attached to 135th Field Rgt on 3 February. On 5 February the Japanese guns moved into position across the straits and the regiment engaged in counter-battery (CB) fire missions against them. Roving sections were used so that the permanent artillery positions were nor revealed to the Japanese. But ammunition was restricted to an average of 20 rounds per gun to conserve stock for a long siege, and this was halved on 7 February. The gun areas, wagon lines and OPs came under Japanese fire and the telephone cables between guns and OPs were frequently cut, but the regiment (with its experience of coast defence deployments in the UK) had duplicated and even quadruplicated some of its links. A joint 135th Field Rgt/4th Mtn Bty OP under an overhanging rock at Bukit Mandai received 25 direct hits but the FOOs (Capt G. Keane, 135th Feld Rgt, and Jemadar Jogindar Singh, 4th Mtn Bty) remained at their posts, bringing down fire on the enemy's gun flashes, and temporarily silencing the guns firing on the naval base.