On 17 April, Major General Gascoigne led a patrol, made up of all the available soldiers of the Hong Kong Regiment, to scout the area for any sign of the Chinese. It appeared the militia had moved to a different position and had entrenched at the head of the Lam Tsuen Valley (林村凹). However, Gascoigne had failed to notice their new position and ordered the patrol to return to camp. Upon seeing the patrol turn their backs to them, the militia took the opportunity and came up behind the British patrol. The British patrol and General Gascoigne remained unaware that they were being approached until the British signalling posts alarmed the British patrol that the Chinese militia was approaching from behind. As soon as the Chinese militia reached the crest of the She Shan (社山) ridge, they opened fire upon the British signallers upon Ma Wo Hill.