Trench warfare is where the two opposing armies, 'dig in', creating a network of interconnected defensive positions, often fronted with barbed wire. These consist of trenches and dugouts which provide troops shelter from the danger on the surface. This form of warfare arose when advances in artillery where not matched by advances in mobility. Between the two lines is the area of 'No-Mans Land'. Attacks were typically bloody, however successful they were. Trench warfare occured during the American Civil War, the Russo-Japanese War and was particularly common and deadly on the Western Front of World War One.