Firework shows have long been a centerpiece of night time entertainment offerings at amusement parks and theme parks, enticing guests to stay later (and spend more money in the process).

In 1978 under Six Flags ownership, Great Adventure looked to expand the entertainment offerings into the night to encourage guests to stay later. The "Magic 'til Midnight" ad campaign help bring the guests to the park and things like fireworks shows kept them until closing. Initially the waterway in front of the Fort was used for these shows with mortars being placed in the water. Due to the proximity of the Fort and adjoining walkways, the size and scope of the fireworks shows was limited.
Fort Fireworks Shows from 1978 to 1982

Each season from 1978 through 1982 Lahaway Creek in front of the Fort played host to the fireworks shows which ran nightly through the summer. Each season's show was tweaked slightly and set to different music to keep it fresh for returning guests.

1980                         1981
The 1982 season's show was somewhat different, forgoing the rock music of past seasons for Broadway show tunes. In addition, the Fort featured a giant lit sign that said "BROADWAY" on one of the towers which was illuminated as part of the nightly shows.

The Fort fireworks were smaller "ground display" type shells which reached limited heights. Many of these were more like roman candles than traditional fireworks people think of in 4th of July shows though postcard images suggest that larger shells may have been launched behind the Great Arena as well (though that may just be an artists embellishment for the postcard). 

The proximity of the fireworks to the Fort also necessitated closure of the Runaway Mine Train and the Skyride, two of the parks most popular attractions. These closures were temporary from just before the show began until just after it concluded each night.

The 1982 season was the last of the shows done from the lake in front of the Fort, with the "Great Lake" (AKA Switlik Lake) becoming the new setting for fireworks in 1983 with the addition of the Great Lake Grandstand for the daytime Water Ski Spectacular shows.  
From Photo to Postcard