He built a wall around Rome to protect it
He built the Aurelian wall as a defense.
He built a wall around Rome
To build a wall around Rome
He divided the empire in half so that it would be easier to defend
He built a wall around Rome
increased poaching and collection of firewood etc
The first threat Marcus Aurelius ad to face was that of the Parthians (Persians). The war with Parthia was initially conducted by the governors of Cappadocia and of Syria, but they were both defeated. Three legions (from Bonn, Budapest and Bulgaria) and a unit from Vienna were sent as reinforcements. The war with Parthia was fought and won by generals. The redeployment of troops to fight this war weakened the northern frontiers of the empire. Marcus Aurelius reacted to the waves of invasions in this area by leading the Roman troops himself, together with his co-emperor, Lucius Verus. After the death of Verus, he conducted the Roman campaigns himself. Marcus Aurelius spent thirteen of the nineteen years of his reign fighting the Marcomannic Wars.
Mainly Leopard seals but any Marine carnivore will take a bite if the opportunity presents itself.
The Himalayas in the north and the Hindu Kush in the northwest served as natural barriers that protected India from outside invaders. These mountain ranges made it difficult for invaders to cross into the Indian subcontinent, providing a natural defense against potential threats.
The skin immune system acts as a barrier against harmful invaders like bacteria and viruses. It detects and fights off these threats to prevent infections and maintain the body's health.
By ruling out a series of threats to that validity. Please see the link for a list of them.
emperor guangxu's efforts to reform and modernize china failed because many qing officials saw these reforms as threats and placed guangxu under arrest effectively reversing his reforms.