By the time the seawater finally rose to the feet of Castel Cathedral, it began to recede.
The cathedral's concrete walls were absurdly thick. The sections near the furnace were even six meters thick. They had never been intended for actual use, merely added as an extra margin of safety.
Yet those heavy walls saved Castel.
The sudden rise of the sea and the monsters had caught everyone off guard. The outer fortifications had been designed for the intensity of human warfare, built only to withstand bullets and explosions. No one had ever imagined towering beasts several stories high smashing into them head-on.
As a result, the outer forts could not withstand the sea urchins' mass assault and fell one after another. Had the retreat order not come quickly enough, the casualties would have been unbearable.
But by the time they reached the cathedral, there was nowhere left to retreat. They could only rely on the massive fortress walls and hold on.
Fortunately, they barely managed to withstand it.
The Faithguard Army inside the fortress took cover while large numbers of explosive packs and ignition targets were laid outside. The soldiers tracked the sea urchin monsters' positions, then shot the prepared fuel to detonate the explosive packs.
The results were fairly good. Without the Banshees throwing explosive packs, they successfully slowed the monster army's advance.
And the sea urchin monsters' devastating charges finally came to a halt before the cathedral's thick concrete walls.
They charged again and again, slamming into the walls until the sea urchins' spines broke, yet the reinforced concrete remained unshaken. At last, several walls were smashed open, and smaller Fishmen crawled inside, engaging the Faithguard Army in another defensive battle within the fortress.
The Faithguard Army stubbornly contested every line of defense with them, holding out