en_tn/2ch/11/11.md

He fortified the fortresses

Here the word "fortresses" refers to fortified cities. That Rehoboam "fortified the fortresses" means that he built up and strengthened the defenses of these fortified cities. AT: "He strengthened the defenses of the fortified cities" (See: rc://en/ta/man/translate/figs-explicit)

made them very strong

"made the cities very strong"

Judah and Benjamin belonged to him

Rehoboam was in control of the tribes of Judah and Benjamin.