The Frontline is a collection of multiple community-created models, textures, particles, overlays and skyboxes, made for Hammer Editor and Source Filmmaker users to create 20th century warfare styled custom maps and SFM movies. Such models and textures included in this pack include, but are not limited to; armored cars, barricades, jeeps, tanks, and sandbags.
The earliest work on the Frontline started in January 2015, and it is still under active development.
The Frontline can be downloaded from http://frontline.tf/