New tactics and weapons took away the war of mobility until inventions like the tank started to get the war mobile again. Inventions like the machine gun which was heavy two to three man operated weapon until the advent of the sub machine gun. The shrapnel shell and barbwire made the battlefields killing grounds the only option for a soldier to survive was to dig into the ground, then fox holes were connected with trenches and the birth of trench warfare was born. Ultimately the generals were favoured into a war of attrition with their out dated tactics (The last man standing wins) but when all sides started losing too many men, then new technology was being employed like the tank.