Pentos is one of the largest of the free cities of Essos but considered the weakest of them all due to the constraints placed on them by Braavos during their last war. Pentos is not allowed to hire mercenary companies, keep slaves, keep a standing army, and limited to a navy of twenty galleys. With all these limitation on their power Pentos is frail, but they have been able to find some creative ways to get around the disastrous peace terms dictated on them.
Many of the Pentoshi ships can be easily converted into military service though they remain under the ownership of either a trade guild or spice guild. The spice guilds have become the de-facto army of Pentos and man the cities defenses. While these things give Pentos some level of defense, they primarily rely on good diplomacy to prevent their destruction at the hands of the Dothraki or their neighbors.