Following developments in the course of the Battle of Verdun by mid June there was discussion about bringing the date of the Somme offensive forward, and 25 th June was agreed to, with 29 th June as the latest date to make the attack. As it happened, the date was moved to 29 th June. But on 28 th June the weather was very wet, causing trenches and gun positions to become waterlogged. The attack was postponed until 1 st July. It continued to rain on the night of 29 th /30 th , but the morning of Saturday 1 st July dawned as a dry day with a cloudless sky, with a mist lying in the river Somme and river Ancre valleys, and the prospect of a warm, sunny day.
The 42nd Division transferred from Adam's III Corps to Lieutenant General Michael Barker 's I Corps on 19 May 1940, nine days after the German Army invaded France , as the division moved into the front line on the River Escaut .  On 17 May Brigadier John Smyth 's 127th Brigade was detached to join "Mac Force", under Major General Noel Mason-MacFarlane , temporarily leaving the division with two brigades, returning on 20 May.  After the speed of the German advance, the division, along with the rest of the BEF, was forced to retreat to Dunkirk , and was evacuated from Dunkirk on 31 May/1 June, having suffered significant casualties.  Around this time the 42nd Division gained its first and only Victoria Cross (VC) of the Second World War, belonging to Captain Marcus Ervine-Andrews of the 1st Battalion, East Lancashire Regiment , of the 126th Brigade. In addition to being one of the first VCs won by the British Army during World War II, he was also the first Irishman to be awarded the medal during the war.