July 1, 1916

First day on the Somme

Opening day of the Battle of the Somme

Two mines erupted beside La Boisselle at 7:28. Two minutes later the whistles went — and by nightfall the British Army had suffered 57,470 casualties.

7:28 a.m., 1 July 1916

British tunnellers detonated the Y Sap and Lochnagar mines beside La Boisselle at 7:28 a.m. on 1 July 1916, two minutes before the infantry's zero hour. The Lochnagar charge was 60,000 pounds of ammonal; Y Sap held about 40,000.

At 7:30, fourteen British divisions attacked the German Second Army north of the Somme while French forces attacked farther south. Several other mines were fired along the front — these two were the prominent ones, not the only ones.

Progress in the south, catastrophe in the north

French forces made substantial progress in the southern sector, and the British achieved some local successes on their right.

Across most of the British front, surviving German troops emerged from their dugouts and stopped the advance with machine-gun, rifle and artillery fire. The Newfoundland Regiment's war diary said its men were “mown down in heaps” while trying to pass through their own wire; its attack had failed by 9:45 a.m.

57,470 casualties on 1 July

The British Army suffered 57,470 casualties on the day, including 19,240 killed — the highest single-day casualty total in its history. Casualties there means killed, wounded and missing, not deaths.

Haig ordered the offensive to continue.

Sources

Researched 23 Aug 2026 8 sources 2 audit passes

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What the sources leave uncertain

The British figures 57,470 casualties and 19,240 killed are the standard official totals. “Casualties” includes killed, wounded, and missing; it does not mean deaths.
Different accounts count the opening mine charges differently depending on whether small camouflets are included. Y Sap and Lochnagar were two prominent explosions, not the only mines fired.