Well, at the start of the war, yes. It was soon realised that cavalry charging machine guns leaves you with a lot of casualties. So entrenchment began. Although, old tactics were initially used against modern equipment, these were shown to be ineffective and new strategies were being tried out. They experienced 'growing pains' that cost the lives of many men. If you compare tactics at a point the same point each year, they are vastly different. Just many of them don't work. Look at the use of tanks, aircraft, automatic weapons, indirect fire weapons and thing like that. They are all things that were brand new and generals had to account for and plan for.