Casualties are 15 000 for the British with another 7 000 Prussians. The French lose about 25 000 with another 8 000 prisoners. Thre French have 220 guns captured ! Nearly 200 000 men on a single day...
65 million men were mobolised during WW1, and 8.5 million were killed, 21 million were wounded, and 7.7 million were POWs
So just over 1 in 7 soldiers were killed
A further 1 in 3 were wounded
And...