Castle Arrow Slits

Castle arrow slits also know as arrow loops, loopholes or loophole were thin vertical gaps in castle walls that medieval archers could fire arrows on enemy attackers!

Arrow slits were so thin that they also protected the archers body from enemy weapons that were fired against him.

  • Definition Arrow slits.
  • Arrow slits, arrow loops, loophole and loopholes.
  • Arrow slit Description.
  • Purpose of Arrow slits.
  • Arrow slits in the defense of a medieval castle.
  • Types of Castle Arrow slits.
  • History of Castle Arrow slits.


Castle arrow slits were a clever design as the stone in the castle wall the surrounded the arrow slit hole were cut at an angle and built into the castles design

This oblique angle allowed the castle archer to be able to move around the arrow slit and made it possible for an archer to fire his arrows at a wider target than would have otherwise been possible.

The arrow slits shape was dictated by the weapons that would be fired from it.

Crossbow weapons required a low arrow slit as they were easier to load and fire from a crouching position, whereas longbows were very long and the longbowmen needed to stand upright, this determined that the arrow slit would be much longer and possibly wider as well.

Finally round shapes were also added to the ends of the arrow slits that made it easily to aim a shot for the archers, these were called “Oilets”.

  • The Length of Arrow slits varied but could be up to 9 feet in height to accommodate longbowmen weapons.
  • Crossbows were fired horizontally from arrow slits, longbows vertically.
  • “Oilets”, (round holes at the ends) were added to arrow loops to help the archers aim their accuracy and range.
  • The cross shape formed by the vertical and horizontal arrow slits resembled a crucifix.

Castle Arrow Slit Inside

Castle Arrow Slit or Arrow Loop from inside castle

Parts of a Castle – Arrow Slit

The bottom of an arrow slit opening was called a fishtail, behind the arrow slit was a recess that helped the archer to move into the space to get a better view and freed up some space for movement, this was called an embrasure.

Some medieval castle also incorporated horizontal openings in addition to the vertical arrow slit opening which also improved the range of vision.

Horizontal openings were later added as the archer had a limited field of vision and could not see the attackers unless they were in a very limited field of vision.




  • White Castle in Wales has a horizontal opening that was added to it’s vertical arrow slit opening.
  • An arrow slit or loop were sometimes cut away at an oblique angle to improve the field of vision.
  • A Balistraria is an arrow slit with vertical and horizontal lines cut into the stone that forms a cross shape.


It is believed that Arrow slits were first created in ancient times by Archimedes around 214BC.

Arrow slits were also recorded in Greek and Roman literature and Art, however arrow slits seem to have gone out of favor for a period that incorporated the Norman invasion period.

The use of arrow slits as a defensive feature of medieval castles was re-established around the 12th century.

In earlier designs castle arrow slits were mainly vertical thin gaps in the walls and had a limited field of vision and each archer was in charge of defending a small section of the castle walls which was his responsibility.

As arrow slits became more advanced and the openings were better designed a medieval archer was able to defend a larger part of the castle wall and his vision was better and the angles that he could fire his arrows from was greater.

It wasn’t until around the 13th century when castle designers demanded that arrow slits should be positioned all around the castle and it’s walls.

  • Dover Castle was designed with a narrow arrow slit with limited vision.
  • Framlingham Castles also has a dated type of arrow slit with limited all round vision.
  • The Château Gaillard in France also has a similar arrow slit design.
  • White castle in Wales has more advanced arrow slits called “displaced traverse slots” that give better defense.

Windsor Castle Arrow Slit

Inside View of Arrow Slit of Arrow Loop of Windsor Castle

Types of Castle Arrow Slit

There were various arrow slit shapes also called arrow loops and other names.

The basic arrow slit shape was a thin vertical line, the limitations of this original arrow slit shape led to the creation of an added horizontal line that improved all round vision.

These horizontal lines were added at the eye height of the archers which gave the arrow slits the look of a religious cross, this type of arrow slit was called a Balistraria.

Displaced transverse slots or slits were another design that helped to protect the archer inside the castle by creating a smaller target for the attackers, these were offset slits that worked well.

Embrasures built into the castle wall design could allow several archers to fire from the same arrow slit at the same time, this made rapid fire of arrows on the enemy attackers possible.

  • Corfe Castle had lockers for the archers where they could store ammunition such as bolts and arrows.
  • Embrasures built into arrow slits allowed multiple archers to fire from the same arrow slit.
  • The cross shaped arrow slit is called a Balistraria.
  • Arrowslits were around two inches wide from the outside position of a castle.

We hope you found this article on arrow slits, arrow loop, loopholes factual and informative, we suggest you look at our other articles in the castle parts section that will help you expand on your knowledge of castle arrow slits and give you a greater all round understanding of arrow slits and castle defenses.

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