Why did the western front bearly move through world war 1?

The largest factor is due to a cross between much of the traditional military tactics being met with modern machinery. During this time, much of the chain of command in both the triple entente and the triple alliance were using the same military tactics that much of Europe (and for that matter the world) had been using for over a thousand years. This same single file and rank order of one continuous of men to charge into battle were no match for the machine guns and upgraded pistols as well as artillery which were rapidly being produces and improvised in the advancement of this new "modern war." Many of the head of command during this time even talked about and admitted in many of their journals that they thought the machine gun fire would not be able to mow down as many of their men as they had assumed because they believed it would not work on the battlefield.