How did the trenches develop?

• Britain declared war on Germany on August 4th 1914.
•  The British Expeditionary Force (BEF) was sent to France to stop the Germans advancing through Belgium.
•  Soldiers began to dig small trenches to shield themselves from machine gun fire.
•  Stalemate developed - neither side could advance, so both dug in to hold their ground. Eventually a line of trenches stretched from the English Channel in the north to Switzerland in the south