A Very Basic
Introduction to Tactics

(Tac 101)

This page is intended as a very basic introduction to Civil War era tactics. Many of the principles apply to different degrees on different scales to other eras. Those familiar with ground combat can easily skip this page, and go on to the First Day of Fighting page. Those less familiar with combat might wish to pick up a few basic principles that help understand how the field was used.

The basic formation for both attack and defense was the line. Men fought two ranks deep. By holding a line formation, the maximum number of men could fire towards the enemy without risk of hitting one of their own people.

A Union reenactment company demonstrates a small line formation. Here, the front rank is ready to fire as the rear rank reloads. Note the ramrods of the men in the back rank as they push the powder and bullet to the bottom of their barrels. Two deep is the practical limit, the most common depth of a line. Men were spaced 28 inches apart. Thus, 20 men in a line two ranks deep would cover a line 280 inches wide, or 23 feet. An under strength regiment of 200, ten companies similar to the one shown above, standing side to side, might cover a front of 230 feet.


The above is an undersized company, about 20 men. Normally, 25 to 40 man companies were more common. With ten companies in a regiment, most regiments had roughly 250 to 400 men. Regiments at the beginning of the war were larger, sometimes approaching 1000 men, but reinforcements generally came as new regiments, rather than as soldiers to fill out veteran units. Thus, older regiments became smaller. Eventually, several old small regiments might be combined to create one effective regiment. A regiment is normally led by a colonel, though majors often assumed and maintained command of regiments.

Three to five regiments might be combined to form a brigade, roughly 1,500 men,generally led by a brigadier general. Two to four brigades form a division, about 5,000 men, led by a brigadier or major general. Two to three divisions form a corps, about 15,000 men, led by a major general. Armies were also led by a major general. The armies at Gettysburg were somewhat under 100,000 men one each side.

(The next rank higher than major general was Lieutenant General. The first US general to hold this rank was George Washington. There was a reluctance through much of the Civil War to promote a second man to a matching rank. Thus, a division, corps and army commander might all have the same rank. Eventually, U.S. Grant became the second Lieutenant General.)

The 135th anniversary reenactment of Pickett's Charge
Lots of reenactors here, but their regimental fronts are
still smaller than historical.

The Confederate units were generally larger then their Union opposites. In the maps shown in these pages, Union Corps are frequently shown in roman numerals, while confederate divisions are shown by the name of their commander. This is how the two armies identified units during the war. I have decided to show 7 Union corps and 9 Confederate divisions on the maps as this gives the largest number of units that can be reasonably shown on a map that downloads on the web reasonably quick.

The AoP had seven corps and Gettysburg, which is a high number of units for a single general to command. A general will only be able to handle two or three units. Thus, the Union quite often used "wing commanders," generals in charge of two or three corps, creating an temporary level of command between the corps and the army. Thus, Reynolds commanded the I, II and XI Corps at the start of July 1, while Hancock, Warren and others at times held command over parts of the field.

The Army of Northern Virginia had only three Corps, thus had less need for wing commanders.

Attack v Defense

The defender can load and fire at the maximum rate. Civil War muskets were muzzle loaders, impossible to load while moving. The attacker would have to pause exposed to return fire. The defender can also choose high ground with cover, while forcing the attacker to expose himself on open ground.

It is not an accident that this page was done with attackers in blue, the color for the Union on my illustrations, while the attacker is in Red, the color used for Confederates. (Gray doesn't show well against the green and white Bryce maps.) While there minor exceptions, the Confederates held the 'initiative' for the entire battle. Lee chose the time and place of the attack, and thus had the attacker's advantages.

Confederate forces, especially on July 2nd, were pressuring the Union flank positions. During the Civil War, if one's flank is turned, holding one's position was essentially impossible. The flanked unit would be forced to withdraw. On the afternoon of July 1st, the Confederates turned both flanks of the Union force north of town, forcing the Union to retreat in disorder. On July 3rd, the Union was able to turn both flanks of Pickett's Charge, with a similar result.

The defender would respond to a flank maneuver by curving their lines away from the attacker to make their flanks difficult to reach. In turning Pickett's Charge, they were also able to pivot forward to hit Pickett's and Pettigrew's flank. Both the 20th Main at Little Round Top and the 69th Pennsylvania at the Angle refused their flanks, curling their lines back. (While the above illustration shows a unit both refusing a flank and pivoting forward to hit an opposing flank, doing both at once is highly unusual. To my knowledge, nothing similar to the above illustration occurred at Gettysburg, though both maneuvers were used by different units during the height of the attack on the Angle.)

As a result of Confederate efforts to stretch towards Union flanks, and Union efforts to protect their flanks, the Confederates had exterior lines. This is especially true near Culp's and Cemetery Hills. There, Union troops were often moved from one threatened point to another. The Confederate troops east of town were isolated, could not quickly help other units or be helped by other units.

Next : The First Day