Although often referred to as "battles" these affairs were more accurately "offensives" comprising a series of individual battles covering a sector of the front.

For example, Third Ypres comprised of the following battles (though this might vary according to what defines a battle and what defines a lesser action)

Battle of Messines - June

Battle of Pilckem Ridge - July

Battle of Westhoek - August

Battle of Hill 70 - August (a diversionary operation)

Battle of Langemarck - August

Battle of the Menin Road Ridge - September

Battle of Polygon Wood - September

Battle of Broodseinde - October

Battle of Poelcappelle - October

First Battle of Passchendaele - October

Battle of La Malmaison - October

Second Battle of Passchendaele - October

In between these would be numerous smaller actions perhaps not warranting the title of 'battle'

For much of the war, battles were ‘set-piece’ affairs. In order for the attacking side to stand any chance of success, it was necessary to stage a preliminary bombardment to destroy or neutralize enemy artillery, cut barbed wire, and demolish fortifications. The volume of artillery fire required was colossal. It would take weeks to register the fall of shot of all the guns, vast quantities of ammunition had to be stockpiled, and the bombardment itself could last a week. This all gave the defenders adequate notice of what was afoot and robbed the attacker of any element of surprise.

Once the attack was launched, a detailed fireplan was executed with a creeping barrage – a curtain of fire – being laid down, behind which the attacking infantry could advance with relative safety and with a reasonable chance of success.

However, the lack of portable radios meant that once an attack was underway, the Generals were unable to coordinate the battle.

Thus, once the initial attack went in, the attackers were faced with rapidly diminishing returns as no careful planning was possible beyond the initial stages, and the defender could more easily reinforce any threatened sector (the attacker would have to drag artillery and supplies across no-mans land with no roads or other infrastructure).

Hence the general character of the war of often successful set pieces which then rapidly bogged down into attritional slug-fests.

Battle would then be broken-off and relaunched after more preparation, which could take weeks in the same sector or months in a different sector.

Eventually, advances in artillery meant that the very long and expensive bombardments could be dispensed with in favour of short, sharp, ‘hurricane’ bombardments. This allowed the element of surprise to return to the battlefield, and along with vast improvements in logistics and staff work, meant that the axis of attack could be switched in a matter of days.

By the 100 days offensive that lead to the Armistice, the practice of constantly switching the axis of attack kept the Germans constantly off-balance and avoiding the problem of rapidly diminishing returns in a style of fighting that has been termed ‘rolling attrition’.