Caleb didn't immediately leave the borderlands once he defeated Malrik and his vice-commanders. He stuck around to observe their actions.
Furthermore, he needed to rest after having a rather hectic night filled with ups and downs.
The fight he had with the commanders was one of the hardest he had ever experienced. He had to give his all, both physically and magically.
His combat skills were unimpressive, but combining that with his explosive speed boosted by his almost unlimited mana gave him the advantage.
Fortunately for him, his fire domain and light-stunting ability played a major role in aiding him to defeat the commanders.
'But who am I also kidding?' Caleb couldn't help but chuckle at such thoughts. 'I fought four strong individuals almost on par with me, and I defeated them — I made it look easy.'
The fort was gone, and the strength of the Growian forces was crippled. Whatever plans they had would have to be pushed back.