Lowe returned to the Army of the Potomac now under General George McClellan, with his new military balloon the "Eagle", though his generators were not ready. He performed ascensions over Yorktown, after which the Confederates retreated toward Richmond. Lowe was given use of a converted coal barge, the "George Washington Parke Custis", onto which he loaded two new balloons and two new hydrogen gas generators, with which Lowe performed the first observations over water thereby making the "GWP Custis" the first ever aircraft carrier. In Lowe's Official Report to the Secretary Of War, he stated: