'On the night of the 24th October 1918 at Pont a Pierres when his section was proceeding into the line a water cart of the 3rd N.Z.R.B. became bogged in the road in consequence of which the traffic on both sides of the bridge was blocked causing a dangerous, congestion. The enemy was shelling heavily with 8 in shells and gas. Notwithstanding the heavy shelling Sergt Coster with the greatest coolness and decision procured horses from his section limbers and assisted by 24/673 Corporal Alfred Edward Collins (of his section) proceeded to attach the teams to the water cart which was eventually extricated and the traffic allowed to disperse. Throughout the whole proceeding Sergt Coster displayed the greatest disregard for danger and his behaviour generally in precarious situation was a fine example for all and there is no doubt that his prompt action saved many casualties in his section and among the transport generally.'
Source: London Gazette
Date: 17 June 1919