During the opening months of world war 1 the fighting was mobile as the Germans pushed through Belgium and into France. Then were pushed back at the battle of the Marne. I was wondering how soldiers were deployed in this stage of the war? Did they still use tactics like moving up as a line, shoot and charge? How did they advance and take positions, especially when up against machine guns? Also how was artillery used to support infantry when things were constantly in motion?
Thank you for your time.
^ these previous answers I've given should be pertinent
I was wondering how soldiers were deployed in this stage of the war? Did they still use tactics like moving up as a line, shoot and charge?
Despite popular memory of 1914, no, they did not use Napoleonic line as standard tactics. The training manuals of virtually all the major armies at the time emphasized advancing via fire-and-movement, in dispersed skirmisher formations. Based on their experiences in the Second Anglo-Boer War, British regulars were also schooled rigorously in cover-and-concealment, while Russian infantry were instructed to entrench or find cover wherever they halted, based on experiences in the Russo-Japanese War. German training was similar, though it seems that junior officers liked to keep their ranks close up until the last second before attack or being fired upon, to give them greater control over their unit, and this may explain British accounts of 'lock step' Prussians (though these are obviously exaggerations).
In the French case, Grandmaison's 1913 training manual emphasized thoroughly preparing each attack, and reconnoitring before had, while advancing dispersed under the support of artillery and machine guns. Unfortunately, the need to allocate funds and the late re-adoption of the three year service law, as well as infrequent pre-war maneuver, meant that French troops were often poorly trained in these methods. The result during the Frontiers was that some French units were ambushed in marching columns by German attacks, or bunched together in attack. This was due to the absence of Grandmaison's tactics, not because of them. The French also experimented with drab uniforms in 1913, and had decided to adopt the Bleu Horizon in 1914, though it was not ready until 1915.
How did they advance and take positions, especially when up against machine guns?
I believe this is covered; as to Machine guns, training pre-war emphasized thorough training to enable accurate shooting (often indirect) and quick set-up and manoeuvre. They were mostly used to provide supporting fire for the infantry, and to secure flanks and defensive positions.
Also how was artillery used to support infantry when things were constantly in motion?
Artillery was mostly horse drawn, though some was motorized. The light weight and mobility of the French 75 proved an advantage when shifting forces to the Marne, though a lack of heavy artillery was felt by the French. Battles themselves weren't exactly in 'constant motion', so there was time to set up and lay the guns, and then to provide fire support.
EDIT:
I'd also highly recommend these lectures by [Nicholas Murray] (https://www.youtube.com/watch?v=2cbq7iu8FrI) and [Spencer Jones] (https://www.youtube.com/watch?v=ij1Gx-cF8-A)