Camp Borders

The Camp Borders are magical defenses that surround Camp Half-Blood and Camp Jupiter.

Camp Half-Blood
Camp Half-Blood has magical borders that go around the entire camp. The border acts as a shield from mortal eyes, making anyone that looks at it see nothing more than a strawberry field. The border also keeps out any type of weather that the gods don't want, including rain, snow, or even high winds. The border will also keep any any being that isn't a demigod, unless they are invited inside the border.

The camps borders primary use however is to keep out intruders. As monsters are drawn to the smell of demigods, the magical borders were used to keep the camp safe from monsters. However, originally the borders weren't strong enough to keep out more powerful monsters, so the camp had other defenses. The Hephaestus Cabin built a large mechanical dragon in Bunker 9. The Bronze Dragon would patrol the borders of the camp and attack any monster or enemy that threatened the borders. The dragon however eventually went haywire and disappeared into the woods for many years.

Eventually, the demigod Thalia Grace raced to Camp Half-Blood with two other demigods named Luke Castellan and Annabeth Chase, along with a satyr by the name of Grover Underwood. While Thalia held off a large group of monsters sent by Hades, the others raced past Half-Blood Hill. Thalia however bought them as much time as she could before almost dying. Zeus, her father, felt sorry for her and turned her into a large pine tree. The magic of the tree strengthened the overall power of the border, preventing even the most powerful monsters from entering.

It is unknown how the border distinguishes between allies and enemies of the camp. For example, mechanical monster like the Colchis Bulls were affected by the shielding properties of the border. Also, several Skeleton Warriors managed to get past the magical borders. It is also unknown if the borders keeps out enemies of the camp, such as demigods that joined the Titan Army. However, the borders only prevent monsters from entering the camp and monsters can be summoned inside the borders.

Camp Jupiter
Camp Jupiter had several different borders that keep the camp safe, as well as the inner city of New Rome. The borders are upheld by Terminus, the god of boundaries. There are several statues of the god all over Camp Jupiter and they all monitor the borders. The borders of Camp Jupiter function much the same as Camp Half-Blood. The borders shield mortal eyes from the camp, as anyone that looks at the camp will only see a large open field.

The border isn't as strong as Camp Half-Blood, which has Thalia's tree to boost its' power. However, it is strong enough to provide some protection against monsters. Terminus himself will also see groups off when they leave the camp. Once you get into the inner city where the senate is, Terminus will prevent weapons from passing him. Even magical weapons, such as Riptide, will be kept outside the inner border and won't return to Percy's pocket.

The Lightning Thief
When Percy Jackson first arrived at the borders of Camp Half-Blood, all he saw was a large strawberry field with a farm house at the bottom. While his mother told him to run past a tree to safety, Percy didn't understand that the tree was the border to the camp or why his mother couldn't go past it. After defeating the Minotaur, Percy and Grover where taken into the borders to recover. While being given a tour of the camp, Percy noticed that the rain seemed to be going around the camp and didn't fall within the borders. He is also told the story of Thalia's Tree and how it helps to defend the camp.

The Sea of Monsters
Luke, after leaving the camp, managed to find a way to poison Thalia's Tree. This resulted in the magical borders of the camp becoming much weaker, allowing monsters to attack on an almost regular basis. While the borders were weaker, monsters still had a hard time getting past them. During the fight with the Colchis Bulls, they slowed down once hitting the border, but were able to get past it with enough effort, unlike Tyson. Tyson, who is a Cyclops, wasn't strong enough to get inside to help Percy. Annabeth gave Tyson permission to enter and the camp's borders allowed him entry.

Because the camp's borders were so weak, the campers had set up a border patrol in order to defend against any more monster attacks, but they new they would be overrun eventually. A quest was given to Clarisse La Rue in order to find the Golden Fleece, an object of strong nature magic that could heal the tree. Clarisse eventually made it back with the fleece and it strengthened the borders of the camp to an even higher level, while at the same time reviving Thalia Grace.

The Titan's Curse
During the winter term at camp, the gods had allowed a small amount of snow to enter the borders. Later, several Skeleton Warriors warriors managed to get inside the border to kill Percy Jackson, but were quickly defeated by Nico di Angelo.

The Battle of the Labyrinth
Luke Castellan knew that his army of monsters could get past Camp Half-Blood's borders, so he tried to use the Labyrinth to find his way inside the borders and attack the camp from the inside out.

The Last Olympian
When Rachel Elizabeth Dare took Blackjack back to Camp Half-Blood to try and take on the spirit of the Oracle, Percy wondered if the magical borders would somehow force her out. However, once she arrived, the borders didn't stop her and she landed safely.

The Son of Neptune
During Percy's arrival at Camp Jupiter, the Gorgons managed to break through the camp's borders and attack Frank Zhang, until Percy used the Tiber River to rip them apart. Later, when going to meet at a senate meeting, the god Terminus prevented him from entering. He was able to tell that Percy had a weapon and made him leave it with Julia. Terminus kept the pen outside the border and Hazel explained that there were border stones all over camp. When leaving for their quest, another statue of Terminus appeared on the edge of the camp borders, where Terminus would see off anyone sent on a quest and give them directions.

Later during the battle at Camp Jupiter, Polybotes chased Percy through the camp and tried to kill Percy. Percy lead him to the inner city where Terminus watched the borders. Once Polybotes passed the inner border with weapons, Terminus agreed to help Percy and they two killed the Gigantes together.