Veterancy levels are those little stars you get above your units. They get them through combat with other units or the destruction of another player or neutral unit's propery.

Basically, the longer a unit lives the more veterancy stars it will have depending on how many enemies it has killed. Any unit with veterancy cannot lose its veterancy unless entirely destroyed. For example a marine squad with 3 stars reduced to just 1 marine will not lose any veterancy.

So you probably noticed that whenever a spartan gets into a vehicle it automatically has 2 or more stars depending on the veterancy of the spartan and the vehicle. This value can increase whenever a spartan or vehicle has had previous upgrades or when either is upgraded while a spartan is in the vehicle.

So when a spartan has no veterancy and gets in a vehicle with no veterancy it will automatically have 2 stars (This DOES NOT increase the amount of XP needed to increase veterancy). When the vehicle has a veterancy it will be added to the spartan's star count. When a spartan has veterancy it will be added to the veterancy of the vehicle's star count.

When a spartan is in a vehicle both the spartan and the vehicle will gain XP and increase the veterancy level together. They also combine their veterancy level maximums into a larger maximum veterancy level. Allowing you to have 14 stars on a Grizzly. Basically playing god

(Spartan upgrades, and vehicle upgrades are applied to the veterancy star count when a spartan is in a vehicle)

When a veterancy star is gained the unit gains one more of those little shields next to their portrait. So one star = +1 shield.

1 Star means dealing 15% more damage and taking 13% less damage.
2 Stars means dealing 25% more damage and taking 20% less damage.
3 Stars means dealing 35% more damage and taking 26% less damage.

These increases are universal to every unit.

I do not know the exact values but you can probably imagine how tough a 14 star grizzly would be just based on these values.

Whenever you upgrade a unit in any one of the unit creation buildings, it will automatically increase its shield count. This does not show a veterancy star automatically on any of the upgraded units, unless it is a Spartan in a commandeered or stolen vehicle.

So basically One upgrade = +1 shield on upgraded units.

The upgrades will generally give a damage or health multiplier to the upgraded unit alongside the main upgrade that the unit gets. These multipliers will stack. This is one of the things that makes staying ahead of your opponents tech level important.

• When playing against the covenant as any UNSC character the covenant may be able to produce more units faster and use their hero to rush you down, getting veterancy levels early and keeping units alive can help tremendously in the earliest stages of the game.
  
  
• Killing the neutral rebel units around the map is a good way to get more veterancy on your units. When destroying a rebel base it is a good idea to destroy all the turrets for your units to gain experience towards higher veterancy and then destroy the main base. When fighting neutral rebels near a position that can be garrisoned it is a good idea to garrison a unit because if the unit has full health it may be able to take on 2 or 3 neutral rebel squads. I cannot recommend this strategy against a neutral enemy like the flood.
  
  
• The user Ferrados Suggested that on the map "Release" you could put Spartans in some vehicles and release the flood on your own base and have the spartans fight the flood in order to gain veterancy. While this can work in a funny way it is not the best of strategies and probably shouldn't be used in a super competitive setting.

Veterancy makes units take less damage and deal more damage. Spartans in any vehicle is a good deal. Upgrading units also makes them tankier and deal more damage (usually).

Thank you everyone who gave some information for the guide. Pretty good deal guys, thanks.
And thanks to everyone who has viewed the guide so far, even if you hated it.

Thanks to...

Syndiwolf
HaloGAMER0329
Tyranocif Pretty much summed up the first half of the comment section with a comment in that very same comment section which is nice
Koel
Ferrados Provided an interesting strategy that I implemented into the guide