How many soldiers?

General McCabe says that every regiment and battalion in the territory would be in the campaign.

And if real life that wouldn't be too many regiments and battalions. In the summer campaign against the Sioux in 1876 that inspired the plot of this movie, for example, detachments from six regiments of infantry and cavalry were involved, and they came from Dakota, Montana, and Wyoming territories.

And in fact General McCabe says that six regiments of cavalry and infantry will be involved in the campaign, like in the summer 1876 campaign. Since a cavalry regiment had 12 companies and an infantry regiment had 10 companies, there would be a total of 62 to 70 companies in the campaign depending on the infantry/cavalry mix. With about 40 to 60 men usually available for a campaign per company, that would make about 2,480 to 4,200 men in the campaign.

If every company of every one of those six regiment was in the campaign. Possibly there are only detachments from the six regiments in the campaign.

When the Third Cavalry leaves Fort Doniphan there are six columns side by side in the parade ground. One is a column of wagons, the others are columns of troops. There are company guidon flags at the heads of each column of soldiers, implying there are only five companies. But if someone spots a second guidon in one of the columns, that would make ten companies.

But if other companies of the Third Cavalry from other forts joined the command offscreen, there could be up to 12 companies in the command at the time of the battle. McCabe sends Captain Harrod with D troop to attack one group of Indians, and then sends Major Marcus with his "squadron" to support Harrod, and then rides off with the rest of his men. A cavalry squadron should have two companies, thus leaving McCabe with 2 to 9 companies (about 80 to 540 men) for his main battle.

I note that a guidon in McCabe's detachment has the company letter "H" and a guidon in a still might have the company letter "K". Harrod's troop D has a guidon with "D", and in the scene where McCabe tells Harrod to attack a group of Sioux the lead company in the column has a guidon with "F".

And I guess that General Hoffman's command would have had the rest of the six regiments or detachments of them, and been much larger than McCabe's command. There could have been one or two thousand men in Hoffman's command, which makes it hard for me to believe that McCabe expected to be victorious attacking with possibly only two companies.

Or maybe General Hoffman only had as many men as McCabe, making McCabe's decision a little more reasonable, and most of the soldiers were in General Osborn's command. If General Osborn's command was delayed by various factors, he might have decided to try the strategy of having Hoffman and McCabe attack the Sioux at the same time.

Of course since The Glory Guys happens in a fictional universe different from real history, Maybe there are only five companies in a regiment in that fictional universe. That would make only about 30 companies and 1,200 to 1,800 men in the six regiments in the campaign.