Marshall, who took over as fourth head coach in program history in August, saw his Hornets (1-0) jump all over Southern Virginia (0-2) in the opening night triumph.
Shenandoah scored the initial 21 goals of the game, including seven in the first quarter and another eight in the second, to cruise to the victory.
The 23 goals is the fourth best total in program history and is the most since SU pumped in 24 goals in a CSAC win over Neumann on April 23, 2008.
Stephen LaTona, who scored the opening goal of the contest just 75 seconds in, led all players with five goals and one assist for six points.
Five other players had multiple points, led by Casey Edsell and his one goal and four assists for five points.
Shenandoah outshot its hosts 48-8, scooped up 23 of the game's 38 groundballs and won 15 of 24 faceoffs.
SU also had four extra-man goals.
Freshman Ben Judy had six saves to post the win in his first collegiate contest.
Shenandoah opens up its home slate on Saturday with a 4 p.m. contest against Alvernia.