battle.wav is a mashup of two sounds, both from projects licensed as (GPL v2 or later)
- ex_med8.wav from Scorched 3D (https://sourceforge.net/projects/scorched3d/)
- Argh_heavy_machinegun.wav from xenoargh's Merc Squad

explosion_01.ogg is just the file of the same name from Starsector, converted to stereo

groundbattle/groundfire.ogg is a mashup of Starsector's Mauler and Hephaesteus sounds

alarm.wav - SoundBible (http://soundbible.com/2056-Missile-Alert.html), modified by Soren
	CC-BY
	
groundbattle/static.ogg - by harveyjnz at Freesound https://freesound.org/people/harveyjnz/sounds/337700/
	CC0
	
groundbattle/cheer.ogg - clipped from a work by Gregor Quendel at Freesound https://freesound.org/people/GregorQuendel/sounds/481781/
	CC-BY