I answered this question (though it was slightly differently phrased) in this thread http://www.reddit.com/r/AskHistorians/comments/25dxyo/what_military_tactics_could_have_been_used_to/ and have slightly rephrased the last paragraph to be more in line with what you are being asked

The factors that the existence of trench warfare were not to do with tactics so much as technology.

Three major factors created a situation where trench warfare could flourish. First, quick fire indirect artillery, secondly the machine gun and thirdly railroads. In 1914 the majority of armies were well supplied with breach loading, quick firing recoil dampening artillery firing shrapnel shot, 'deadly to men in open field but a mere irritant to those in the trenches, the net result of the field artillery was to strengthen whichever force was on the defensive.(1)' Artillery was, and is, the main killer on the battlefield, responsible for 60-70% of all casualties throughout the wars of the 20th century.

The machine gun was not the wonder weapon that it is commonly held up to be by the general public, what it did provide though was a very economical means of generating firepower, one machine gunner could, firing at rapid rate, produce the firepower of 5 or 10 riflemen, and more accurately too. This meant that trenches didn't need to be held in strength, and also allowed for attacking forces to be reduced in strength and disperse without a loss of firepower, where previously, with rifle armed troops, the only way to increase firepower was to thicken the firing line. Effectively, this released a large number of men that could be concentrated out of range of artillery fire, and this is where the railroads comes in.

Advancing troops, under fire from artillery and machine guns, move incredibly slowly, about 1 mile and hour or so. Additionally, reports of a breakthrough are equally slow- telephone lines get shot away by artillery, runners are killed and radios are too heavy, unreliable and unsecure to be fully utilised. In contrast the enemy was able to move his counterattack forces much faster- 40, 50, 60 miles per hour thanks to the combination of the telephone and the railroad. This speed of reaction resulted in a period of warfare where the defender was able to react with far greater speed and accuracy to the events of the war. 'What needs to be emphasised...is that no one solved the problem of converting a break-in into a breakthrough because all the technical means to do so were never available...the only arm of exploitation remained the cavalry'(2) To break the deadlock would require the creation of a effective mobile arm.

So how were these issues overcome? well first, you must create a efficient internal combustion engine. This allowed the creation of reliable armoured fighting vehicles such as tanks, armoured personnel carriers and self propelled artillery. tanks allowed infantry to be supported by direct firing artillery that was impervious to enemy machine gun fire, armoured personnel carriers such as halftracks allowed infantry to keep up with the advancing tanks, while self propelled artillery gave these formations integral fire support to supress enemy anti-tank guns. all this was aided by an improving command and control system. Radios allowed for commanders to ride far forwards with their troops, exploiting opportunities as they presented themselves instead of being tied to the telephone system, also allowing them to react quicker to events than the enemy was able to perceive them. this was tied to a greater emphasis upon mission command, setting your subordinates clear objective and describing your intent for how the battle would end, but leaving considerable rooms for the exploitation of passing opportunism and individual initiative. Aircraft allowed for deep interdiction, destroying enemy transport systems and, in combination with paratroopers, slowing the speed of enemy reinforcements through the seizing of key terrain.

This system of warfare is popularly know as blitzkrieg, 'a combination of the tank, radio communications, and air power in the ancient maxims of offensive action, speed in decisions and the concentration of resources' (3)

(1)English, J.A. and Gudmundsson, B.I., On Infantry, (Westport, Praeger, 1994),p16

(2)Beckett, I.F.W., The Great War, (Harlow, Pearson Education Ltd., 2007),p 235

(3)Bidwell S., and Graham D., Fire-Power (Barnsley, Pen and Sword Books ltd., 1982)p205

The factors that the existence of trench warfare were not to do with tactics so much as technology.