Avenger-class Mine Countermeasures Ship (MCM)

The Avenger class was the U.S. Navy’s only purpose-built mine countermeasures ship class in active service. Fourteen ships were constructed between 1987 and 1994 by Peterson Builders and Marinette Marine at Sturgeon Bay, Wisconsin. The class was designed from the keel up for one mission: finding and neutralizing naval mines in contested waters.

Construction and Design

The defining feature of the Avenger class is its non-magnetic hull — fiberglass-sheathed wooden construction engineered to minimize the ship’s magnetic signature. This is not an aesthetic choice. Magnetic-influence mines detonate when they detect a steel hull’s magnetic field. A conventional warship entering a minefield risks triggering the weapons it is trying to neutralize. The Avenger’s wooden hull allowed it to operate inside minefields where no steel-hulled vessel could safely transit.

The ships carried the AN/SQQ-32 mine-hunting sonar for detection and classification, and the AN/SLQ-48 Mine Neutralization Vehicle — a remotely operated submersible that could identify and destroy mines on the seabed. At 1,312 tons and 13.5 knots maximum speed, the Avengers were slow and lightly armed. They were not built to fight. They were built to clear the path so others could.

Persian Gulf Service

Four Avengers were forward-deployed to Naval Support Activity Bahrain beginning in 2012: USS Sentry (MCM-3), USS Devastator (MCM-6), USS Gladiator (MCM-11), and USS Dextrous (MCM-13). Dextrous had operated continuously in the Persian Gulf since August 1997 — a 28-year unbroken deployment, one of the longest sustained forward deployments of any U.S. Navy vessel. These four ships constituted the entirety of the Navy’s dedicated mine countermeasures capability in the region most likely to face a mining threat.

Decommissioning

The Navy decommissioned the four Gulf-based Avengers in September 2025: Dextrous on September 3, Gladiator on approximately September 12, Sentry on approximately September 24, and Devastator — the last — on September 25. Vice Admiral George Wikoff, Commander of U.S. Naval Forces Central Command, presided over the Devastator ceremony. On January 9, 2026, all four hulls were loaded onto the contracted heavy-lift vessel M/V Seaway Hawk at Bahrain. The Seaway Hawk departed under escort from USS Canberra (LCS-30) and arrived in the Delaware Bay on approximately March 9-10, 2026 — the same day Iran began laying mines in the Strait of Hormuz.

What Was Lost

The Avengers represented 35 years of accumulated operational experience in Persian Gulf mine countermeasures. Their crews trained continuously in the waterways where mines were most likely to be deployed. No replacement system in the current inventory has been tested against real mines in real combat conditions. The Congressional Budget Office noted in 2025 that all eight remaining mine countermeasures ships would be retired within three years under existing plans, with the Littoral Combat Ship mine countermeasures mission package designated as the successor capability.