Hey Guys,

So I'm running a Home brew Campaign, my players (level 3 rogue Arcane trickster, Level 3 UA Ranger (Horizon Walker) LV 3 Paladin (Oath of Vengence) are about to enter embark on a long quest, that in the end, should land them around Lv 10. They are very close to LV 4 as we speak. They'll most likely be level 4 by the time this encounter happens. They all have some nifty Magic items as well. 

Here is the set up: Their current goal is to get to a Location called Covington Outpost, which is located on the top of a sequence of Bluffs. Now when they get to the nearest town, they run into a few soldiers on a supply run for Covington. And so the plan is for them to join the Soliders, and set off for the Outpost. 

Now for the encounter: As they approach the outpost, the Soldiers notice that the first watch at the base of the Bluff is abandoned, which is a red flag. As they travel up the Bluffs they eventually see that the Outpost is being attacked by a BLANK group of Bad guys.

I've been trying to come up with an interesting Large scale conflict. I'm leaning towards orcs, as that makes sense. But I need something that works really well for a large scale battle. I'm also curious about Goblins, but they're unorganized. I'm also not really into Hobgoblins, But I'd love to be convinced otherwise... I like Gnolls, but I'm planning on using those later.

For a Visual, the map is Four tiers, Bottom tier is the Players and three soldiers Middle two tiers is 1 Chieftain style enemy, two Berserker enemies, one Spell Caster, and about 10-15 Grunts (using minion rule from 4e possibly.) the Top tier is Covington outpost, which is 8 Archers, a Spellcaster. I have several hazards planned, boulders, burning Oil etc, and the Orcs have a siege ram going for the gate. 

I have a few contingencies planned. Locations for Reinforcements etc. My players are really hardcore Tacticians we bonded over RTS long time ago, so this is supposed to be a big, challenging encounter. So any advice on enemy type/ implementation is appreciated. 

Thanks!

Before I can go any further is this a .tactical military assault or is this a rage fueled scorched earth attack?

Tactical Military attacked 

  If you plan on using goblins I would recommend using their nimble escape trait to the fullest. Remember that any one attacking from hiding has advantage on attack rolls against targets that they're hidden from. Attacking a creature you can't see also imposes disadvantage, this significantly extends a goblin's shelf life. Once your players are able land an attack however the goblin should go down likely only able to survive a glancing hit from a 3rd level character. Goblin's small stature could also be a tactical advantage on the side of a rocky bluff allowing them to make use of paths that would be difficult terrain to a medium or larger creature. This will also make any halflings or gnomes in the party an asset to the team.

  Be sure to provide your players with ample cover (pg. 196 PHB if you haven't been using it already) and remember that prone creatures impose disadvantage on attacks made from more than five feet away. Attacks made while prone have disadvantage as well but I house rule crossbows the exception to this rule (though the difficulty of drawing the string on a heavy crossbow may call for a strength check).

  I find goblins a great opportunity for some Vietnam style guerilla warfare. Meanwhile Hobgoblins are a Roman legionnaire's,and Samurai's wrath child. Strict, organized, with an all consuming desire for battle glory. Harry your players with goblins then meet them with hobgoblins. Hobgoblins will maneuver to gain their Martial Advantage like a proper legionnaire, but your players can shove or lure hobgoblins out of formation. A few hobgoblins can cut down an adventuring party with just a few targeted take downs, it will be up to your players to outmaneuver and isolate the hobgoblins while the hobgoblins attempt the same. If you want to get into the gritty bits of medieval melee combat you will not find a better example than the Hobgoblin. Given your party composition I would recommend giving them a small taste of Hobgoblin steel then let them rest, and then let them use their stealth to their advantage. Using hobgoblins also allows for the hiring of orc mercenaries (hint hint).

  Hobgoblins will bring the organization the goblins lack and rally legions for large scale conflict. This will allow you to sweep up the third class of goblinoid: the bugbear. The bugbear stat block speaks for itself. Enough health and damage to server your berserker needs, with a healthy stealth skill to keep up with the quiet moving goblins. Hobgoblins will also bring worgs to the party to amplify your goblin hosts tactical ability by introducing some rather gnarly cavalry.

  If your players are tacticians I think they'll enjoy matching wits a great Hobgoblin Warlord. And if you still don't like using hobgoblins relegate them to leadership and logistics roles. Just one heading up some goblins can become a potent foe as even a lowly gobbo in melee with a player is enough to trigger Martial advantage. Hobgoblin strategy oriented thinking will isolate cities and villages without apparent strategic value. These isolated cities and villages serve you well in feeding and bolstering your gnoll horde.

Well, I think you convinced me my friend, Hobgoblins it is! 

My question is: how large scale is the overarching confrontation?  A war?  What over?

Its a territorial conflict. The Bad guys want the Outpost because "Something" drove them out of their own home, and they see the Outpost as being very defensible. The players are currently looking into this "Something".

Something drove them from their homes.  Cool.  Have you decided what that something is yet?  If not, the Mighty Gluestick may have an idea for an invasive species for you here: https://www.youtube.com/watch?v=VrFksOMzwVo