The video game Command & Conquer: Red Alert features a song titled Hell March by Frank Klepacki, which includes a voice sample of an unidentified military officer.
The sample appears to originate in the Series 1000 Sound Effects Library, originally released on reel-to-reel tape in 1979 and on compact disc in 1983, and may also have appeared in Network Sound Effects Library. Series 1000 is described as a collection of sound effects from the 1960s and 1970s, although it does include audio clips from at least as far back a WWII. The sample in question is from Series 1000 Sound Effects Library CD 1019, titled Drill, Military - Footsteps, Orders Being Shouted, Marching, Soldiers 03.
The sample begins with a military officer giving a command, followed by a group of soldiers marching at a pace of around 100 steps per minute. It's not clear what language the officer is speaking, and I'm not sure which modern militaries or parade groups march at this pace (e.g. a quick march of 120 steps per minute seems common). The sample Soldiers 02 sounds like the same officer, and this sample with drums may possibly be from the same event.
A great deal of speculation has been made online regarding what the officer is saying, but most of this is not useful. The most common answers are either complete guesses (i.e. "It sounds to me like he's saying..."), or repeating popular guesses made by others online (most commonly "die Waffen legt an" - I'm very skeptical of this one, since a search for "die Waffen legt an" site:de reveals few results and they're all talking about the video game). In an interview, the song's composer admits that he also does not know what the officer is saying. To be clear, I'm not interested in guesses or summaries of other people's guesses found online.
Regarding these samples, then: