 The Liverpool Pals ' first battle came during " The Big Push " on 1 July 1916 , on the first day of the Battle of the Somme , the worst single day for casualties in British military history . The 89th Brigade , under the Earl of Derby 's brother Brigadier F.C. Stanley , still comprised the 17th , 19th , and 20th Pals , but had the 18th reassigned to the 21st Brigade in December . The 30th Division formed part of XIII Corps , which attacked towards Montauban , south of where Britain suffered the majority of its nearly 60 @,@ 000 casualties on the 1st . At 07 : 30 , the 30th Division began its advance on the left of the French Corps de Fer . Meeting limited opposition , the Pals completed their objectives with comparatively minimal casualties . Grievous losses were , however , incurred by the 18th from heavy machine @-@ gun fire during its advance towards the Glatz Redoubt . The battalion 's commanding officer , Lieutenant @-@ Colonel E.H. Trotter , killed by a shell on 8 July , intentionally underestimated the battalion 's casualties of about 500 to avoid the deployment of brigade reserves . 
