Gas was ineffective when combined with other tactics. E.g. Infiltration tactics 1918.
The main impact of gas was the psychological damage and caused soldiers to live in fear of gas attacks. Finally the Technology of Aircraft was used for spy missions and aerial photographs to discover trench positions. While the R.A.F used machine guns in 1918.
New Technology did not immediately brake the stalemate but most of the technology were used in combination and by 1918 New Technology had contributed to the breakthrough.
America’s entry into the war – 1917 did significantly contribute to breaking the stalemate, and helped break the stalemate immediately. America had the third largest navy in the war so it was going to be hard to beat them. Also the American government was also willing to lend Britain money so it could buy its vital supplies from the United States. Britains food supply problems immediately improved thanks to the wheat they were given by the U.S.A. So that they would not starve and so boosted up the morale and caused Germany a problem, as now Britain had wheat and so were not near to starvation. It signalled the end of the unrestricted submarine activity it also caused huge losses of morale to Germans and signalled the end of Britain being 6 weeks from disaster. Also Germany still had to face a British Blockade, as well as prepare for 1918 and an extra 250,000 U.S.A soldiers per month, as well as fresh enthusiastic, fully equipped U.S.A soldiers. Which put Germany under a lot of pressure and forced them to consider new options.
The U.S.A navy was important too as not only was it the third largest navy in the world but its destroyers could now be used on convoy duty to protect merchant shipping routes between Britain and United States.
Also the entry of the U.S.A into the world increased the number of warships available to defend the convoys and so more U- boats were sunk. Blockade almost broke the stalemate when the Germans launched unrestricted submarine activity for the second time and had destroyed so many merchant ships that there were food supplies for only another six weeks. The British Blockade also came close to breaking the stalemate on the western front as it caused 300,000 deaths which were related to malnutrition, it also cut supplies of nitrates to Germany – which were vital for explosives for the Army and fertilisers for the farmers. While in Germany, the government was forced to slaughter a third of all pigs in 1915 because the naval blockade had cut off imports of fodder to feed them, also in 1916 in Germany the adult meat ration for 1 week was now the equivalent to two burgers. 750,000 Germans had a poor diet due to the blockade, which broke morale of the home front and so led to food riots in Germany but the Army on the western front was still supplied. It was a key factor in Germanys surrender but as we know that is not the question asked. But finally it put pressure on the high command to act quickly and so contributed to ending the stalemate as they resorted to the gamble of a final offensive.
The German offensive of 1918 was probably the most important reason why the stalemate was broken.
The Germans needed to deliver a knockout blow, which meant that they needed to secure a position before U.S.A forces arrived in significant numbers and so in a way it was a gamble.
Next, operation MICHAEL was put into use take the remaining resources of the German Army – basically it was an all out Assault. The aim of this plan was to advance as far as possible and drive a wedge between the British and French Armies.
They were to hit the Allies by using specially trained “storm-troopers” armed with portable trench mortors, flame throwers, stick bombs and light machine guns. They were to attack weaker positions after a heavy barrage. While in 10 days they had advanced 40 days, which signalled the first war of movement in 4 years, whereas the effect on the allied morale was enormous! Haig even issued an order to “fight to the last man”. In a sense Germans had broken the stalemate as in June 1st 1918 they were just 37 miles from Paris and came very close to splitting the allied forces. However General Foch managed to halt the advanced at the battle of Marne, of costs to Germany, as the advance was swift and effective… BUT produced a massive salient, which was 80 miles long and 40 miles deep. Also it was isolated from the left of the forces, difficult to supply and so the middle of the line of advance was the weakest and so many German forces were exhausted. But with this they created their own paradox: As it could be said “the Germans had a very successful result in their failure” as it provided weakened positions for the allies to exploit. But with this we must not leave out the weapons such as Tanks and aircraft’s that were used during the offensive and so contributed to helping the offensive of 1918 along with New Technology, American entry into war and Blockade being important reasons why the stalemate on the Western Front was finally broken.