DUBAI—U.S. Marines early Thursday boarded and seized control of a German-owned commercial vessel that had been commandeered by pirates, in what appeared to be the first American-led military boarding of its kind amid a recent surge of attacks in the Gulf of Aden and along the east coast of Africa.

A raiding party of 24 Marines boarded the ship about 85 miles southeast of Mukallah, Yemen, in the Gulf of Aden, according to the U.S. Navy. Pirates had captured the vessel, which was carrying steel chains, in the same vicinity the previous day, the Navy said.

The U.S. said there were no casualties among the raiding party or the ship’s crew. Nine alleged pirates were captured in the operation.

Somalia-based pirates started to ratchet up their attacks in the gulf and along the east coast of Africa in late 2008. In the spring of 2009, the U.S. military intervened in a pirate attack on an American-flagged merchant ship.