Infantry regiments in the English Civil Wars were supposedly 1,200 men strong, although many were understrength due to casualties, sickness or lack of recruiting. These would be divided into companies. Roughly speaking, there were 10 companies of 120 men each, but each regiment tended to have its own structure.

Each regiment would contain both musketeers and pikemen. Usually these were divided in a rough ratio of 2:1 pike to musket at the start of the war, although each regiment was different. By the end of the war, this ratio had reversed, as most commanders prefered the versitility of the musket.

In addition to these main weapons, most men would carry a secondary weapon, such as a sword or axe for close-quarters fighting.

When on the field of battle, the pike would be positioned in the centre, with musketeers on either side. If it was a major battle, then three or more regiments would join to make a brigade. In this case the brigade's pike would be in the middle, and the musketeers would be divided on both sides, companies would be kept together, but the regiment would be split.

Skippon's infantry regiment portrayed on an old map of a battle. Tactics usually involved the musketeers firing a few volleys into the enemy ranks, and then the opposing formations advancing to meet each other at "push of pike", where each attempted to push the other back physically.

When engaged in "push of pike", there was no room to make use of a weapon, so after the initial contact was made, very few casulaties occured. However, if one side turned and ran, or collapsed upon itself, then large casualties could result.

"Push of pike" was not always reached. Sometimes the morale of one side would be such that it would withdraw or rout before contact was made. At other times, both sides might be wary, and stand apart, jabbing with the pikes as best they could.

If attacked by cavalry in the absence of infantry, then the pikemen would shelter the musketeers, forming the equivalent of a square, but more like a blob. The pikes would protude, keeping the horse away, and musketeers would take opportunities to fire out at any target that presented itself.