Mercenaries: Mercenaries were soldiers who fought for pay, rather than out of national loyalty. Mercenaries were often used by smaller nations or by nations that were short on manpower.
Volunteers: Volunteers were soldiers who fought out of a sense of patriotism or duty. Volunteers were often used by nations that were fighting for independence or for a cause that they believed in.
Militias: Militias were citizen soldiers who were called up to fight when needed. Militias were often used by nations that were defending themselves against an invasion.
Alliances: Alliances were agreements between two or more nations to support each other in war. Alliances could be used to build up armies by providing additional manpower and resources.
In addition to these methods, European nations also used a variety of other methods to build up their armies, including:
* Training: Armies needed to be well-trained in order to be effective in combat. European nations spent a great deal of time and money on military training.
* Equipment: Armies needed to be equipped with the best weapons and armor in order to be successful. European nations invested heavily in military equipment.
* Logistics: Armies needed to be able to move their troops and supplies quickly and efficiently. European nations developed sophisticated systems of logistics to support their armies.
By combining all of these methods, European nations were able to build up powerful armies that were capable of fighting long and bloody wars.