Over at Greyhawk Grognard there's an interestign post on mass combat rules and pittign 1 10th level fighter agaisnt 100 orcs. In the scenario given here http://greyhawkgrognard.blogspot.com/2010/07/1-lord-vs-100-orcs.html the 10th level fighter loses.
With no changes in tactics or equipment the results of the combat will vary by the rules used.
1 lord ( 10th level, AC 0, 50 hit points, with a long sword +2) facing off against 100 orcs (AC 6, 5hp). If you go by the averages, the 10th level fighter loses that battle.
The orcs hit 5% of the time (20 on a d20), and let's be kind and say only 3 of them can attack the lord at any given time. Each orc does averages 4.5 points of damage per hit (assuming 1d8 weapon). In an average round of combat 3 orcs will inflict (4.5 x 0.05 x 3) 0.675 pts of damage on the Lord.
The lord hits 85% of the time (4 or better vs. AC 6). 1 blow per round will mean (6.5 x .85) 5.525 points of damage per round.
The lord will kill all 100 orcs in 100 rounds at 1 blow per round.
The orcs will kill the lord if they can attack 3 at a time in 74 rounds. The orcs win.
Now if the lord is permitted 1 attack per level against humanoids of 1HD or less that lord is going to be dishing out (6.5 x .85 x 10) 55.25 pts of damage a round. He'll be killing 10 orcs a round.
The 10th level lord wins, killing all 100 orcs in 10 rounds.
As scenario 2 but 6 orcs a round can get a hit on the lord.
The orcs will be dishing out (4.5 x 0.05 x 6) 1.35 points a round.
The orcs lose as it will take them 37 rounds to beat the fighter.
The 10th level lord only get 3 attacks every 2 rounds so he's disshing out (6.5 x .85 x 1.5) 8.2875 points a round.
The Lord loses this scenario as it will take him 100 round to kill all 100 orcs.
The orcs finish off the lord in 37 rounds when attack 6 at a time. 74 rounds if attacking 3 at a time.
The lord has double weapon specialization as per UA. He's going to hit 95% of the time (were having a 1 be an auto miss). He's going to get 2 attacks a round so he'll b dishing out ( 9.5 x .95 x 2 ) 19.05 points a round (killing 2 orcs a round).
The lord will kill all 100 orcs in 50 rounds.
The orcs will win as they can defeat the lord in 37 rounds.
The results of 1 lord vs 100 orcs will vary with the combat rules used but the lord is typically going to lose. If morale rules were applied the 10th level lord just might be able to survive some of these fights if the orcs can't keep the will to fight as they watch dozens of allies being cut down before they win and they retreat from the might of the 10th level lord. Tenth level lords shouldn't go into battle alone they should bring friends, henchmen, hirelings and followers whenever possible.