One hundred years ago on July 1 at 7.30am a single whistle blast was blown, the signal for soldiers to leave their trenches and 'go over the top' and advance into enemy territory.

It was the start of the Battle of the Somme, one of the defining events of the First World War.

By the end of the first day, some 57,000 Commonwealth and 2,000 French soldiers had become casualties.

More than 19,000 had been killed.

This morning, the country fell silent in remembrance. 

At Colchester War Memorial in the High Street, crowds blew their whistles before a two minute silence. 

The Royal British Legion laid wreaths and played the Last Post and a crowd gathered to pay their respects.