From various sources:
On the opening day of the battle, the British recorded 57,470 casualties, including 19,240 men killed...
...a Newfoundland battalion fighting at Beaumont Hamel was wiped out in half an hour. Just 68 men responded to the rollcall of 790 names the next day.
(from the NZ Herald)
In our national mythology, the Battle of the Somme remains a sideshow compared to Gallipoli. Yet Major-General Andrew Russell's NZ Division suffered over 50 per cent casualties during its 23-day involvement in September 1916: 2111 killed; 5848 wounded.
The Australians suffered over 20,000 casualties over a 6 week period.
Lest we forget.