CAMDEN, Maine — Retired Adm. Gregory “Grog” Johnson, U.S. Navy, will speak at 7 p.m. Saturday, Oct. 11, at the Camden Opera House on 21st century security challenges.

Johnson, who grew up in Westmanland in Aroostook County, is being sponsored by the Camden Conference.

“He’s got a lot to say, and he’s a pretty interesting guy,” said Kathleen Hirsch of the Camden Conference.

A 1968 graduate of the University of Maine, Johnson began his career as a naval aviator.

He had many years of sea duty, and his career led him to the Pentagon, where he served as executive assistant to the chairman of the Joint Chiefs of Staff.

In 2001, he became commander, U.S. Naval Forces, Europe, and commander in chief, Allied Forces, Southern Europe.

He retired from the Navy in 2004 and settled in Harpswell, where he founded Snow Ridge Associates, which provides strategic advice and counsel, according to a biography.

Adm. Johnson’s decorations and awards include the Defense Distinguished Service Medal with three Bronze Oak Leafs, Navy Distinguished Service Medal, Defense Superior Service Medal, Legion of Merit with two Gold Stars, Defense Meritorious Service Medal, Meritorious Service Medal with two Gold Stars, NATO Meritorious Service Medal, Air Medal, Navy Commendation Medal, Navy Achievement Medal, and various service and campaign awards.