 Haig had discussed the possibility of rapid exploitation of a victory at Messines with Plumer before the attack , arranging for II and VIII Corps to advance either side of Bellewaarde Lake , using some of the artillery from the Messines front , which Plumer considered would take three days to transfer . On 8 June , patrols on the II and VIII Corps fronts reported strong resistance , Haig urged Plumer to attack immediately and Plumer replied that it would still take three days to arrange . Haig transferred the two corps to the Fifth Army and that evening , gave instructions to Gough to plan the preliminary operation to capture the area around Stirling Castle . On 14 June , Gough announced that the operation would put his troops into a salient and that he wanted to take the area as part of the main offensive . On 13 June , German aircraft began daylight attacks on London and the south @-@ east of England , leading to the diversion of British aircraft from the concentration of air forces for the " Northern Operation " . 
