Adam Clarke on Judges 6:24

Gideon built an altar - and called it Jehovah-shalom - The words יהוה שלום Yehovah shalom signify The Lord is my peace, or The peace of Jehovah; and this name he gave the altar, in reference to what God had said, Jdg 6:23, Peace be unto thee, שלום לך shalom lecha, "Peace to thee;" which implied, not only a wish, but a prediction of the prosperous issue of the enterprise in which he was about to engage. It is likely that this is the altar which is mentioned in Jdg 6:26, and is spoken of here merely by anticipation.