I;m about to do a large scale war with my 5e group I'm DMing. This is interesting because at the end of the battle, I add the successes as a set DC for certain events to occur. If the party succeeds this percentile DC by 100% or more (as successes in the battles they are given increase the bonus to the roll, and some failures give a negative to the roll) the party gets minimal casualties (including people they know). For each failure, the same people will die, and more negative events happen.
On an 55% or more, the party succeeds but the fight had some hiccups keeping from a flawless victory. The old and inexperienced died in this one
On a 30%-54% the war ends in a stalemate, both sides taking heavy losses.
On a 15-29% the hobgoblins win but many escape. Many archers and healers are cut down in a flank attack, causing the battle to make a turn towards the hobgoblins winning. The party will only get this low if the party failed to defeat the hobgoblin warlord
On a 14% or less, the hobgoblins decimate the field and all is lost. Many are cut down and slain upon retreating, and trolls, dire boars and ettins take joy in slaughtering people by the dozen.
But what influences this battle is several things: the party succeeding their battles, every NPC they keep alive, and the speed of which they defeat the enemy, and of course, if the leader of the army survives or not.
The leader will prove too strong for the party when they face him, and he will absolutely decimate them in one round, especially on his dire boar mount. But a DM character I introduced who flirts with the party bard often and tries over and over to woo her over, comes in and manages to take him out, but is slain by the warlord as his mount charges away in panic (pulling a part out of Megaman X here sort of). The party will hopefully defeat him and then the results of the fight will happen.
HOWEVER. There is the option to ignore the battle, walk off the battle map and do a "retreat" action where you ignore the fight and you get a big negative to the DC as you doom everyone who is fighting with you in that part (so casualty negatives, failure negatives, and morale negatives).
Since one of my players is running as a leader in this fight, she is running support. I am having her make differnet checks depending on how she wants to boost the morale of her allies. This also adds into the DC of success with her succeeding and picking the right skill check.
There are three main waves and the cavalry lines, as well as medics and support fire (aka archers/mages). The first wave is for the main force, fighting a lot of regular footmen (using numbers more than strength). Wave two will be fighting mostly big brutes and heavy fighters. The third wave, as I call the cleanup crew, will be fighting charging cavalry, brutes AND large numbers. The cavalry for wave 3 will run past and try to hit the players and NPCs, giving them a reflex save to dodge them. If players kill them before they hit the edge of the map, there are more positives added to the roll. Cavalry makes several attack rolls, handle animal checks and a few other checks for hitting their enemy, staying on their mount, keeping grip on their weapon, and if they fail staying on their mount, being able to get back up without getting finished off. Support fire should NOT have to fight, but if there are any players who choose to do that, there will be either a lot of checks to aid in firing constantly, taking out targets, or if you're like me, have a raid come and try to kill them, where they get a combat session. The healers should be making medicine checks up the wazzoo, with maybe one small combat thing happening if things turn for the worse.
I'm also told Tyson-chan will be riding her minotaur buddy as a combat ally/mount to fight off the enemy. This is going to be VERY messy folks, expect a big update on the results of the fight tomorrow