When Abram heard that his kinsman had been taken captive, he led forth his trained men, born in his house, 318 of them, and went in pursuit as far as Dan. 15 And he divided his forces against them by night, he and his servants, and defeated them and pursued them to Hobah, north of Damascus. 16 Then he brought back all the possessions, and also brought back his kinsman Lot with his possessions, and the women and the people.
Abraham trained and raised an army before he needed one. When that time came, he already had men who were trained. Abraham was not threatened by their gain. He was fortified by their advancement. When the time came, he lead his army, divided them and took out kings... plural. Did you catch that? It was previously 4 kings against 5 and Abraham rides into town with a handful of trained men and takes them all out. A handful of sharpened sticks are more useful arrows than a forest of twigs. Taking the time to sharpen men in times of peace produces pointier, more punctual results in times of war.
the more you sweat in peace, the less you bleed in war.