Guidons and the Reason for Custer's Defeat
Guidons are a type of flag used by companies, troops, and batteries, etc, fork tailed, the color of the army branch, with the branch insignia & the regimental number, company letter, etc.
But the US cavalry has used different designs from 1833-1862, 186-1885, and from 1885 to now. From 1885 to the present cavalry guidons are divided horizontally, red above and white below, with the regimental number in white above and the company letter in red below.
In western movies the most common type of cavalry guidon is the 1833-1862 pattern, since it identifies only the company and not the regiment and can be used for any regiment, and the second most common is the 1885 to present pattern. The design with the stars and stripes used in 1862 to 1885, when most most cavalry movies are set, was hardly even seen in movies.
And some movies show the cavalry using guidons, standards, and flags that were never carried by the US Cavalry!
The only western movie that I have seen that explicitly shows that all twelve companies or troops (A, B, C, D, E, F, G, H, I, K, L, & M) of the Seventh Cavalry were present at the Little Bighorn was Custer's Last Fight (1912) a silent film with titles, some of the titles showing the guidons with regimental number and company letter of each detachment of the Seventh Cavalry on June 25, 1876. As far as I know other movies about the Battle of the Little Bighorn are vague about how many companies of the Seventh Cavalry were present.
In The Plainsman (1936) Hickock and Cody meet an Indian who tells them about Custer's Last Stand and has a captured guidon of Company E of the 7th Cavalry. Company E was part of the battalion wiped out in Custer's Last Stand.
Earlier the Cheyenne ambush a troop of cavalry numbering 46 men under Captain Wood, sent by Custer with ammunition from Fort Hays to Fort Piney, and besieged it for over a week in scenes inspired by the Battle of Beecher Island in 1868. Almost all the 46 soldiers are killed or seriously wounded and unavailble for duty at the Little Bighorn soon after.
And the guidon of the besieged soldiers is that of Troop B of an unidentified regiment. If the company B that suffered severe losses was company B of the Seventh Cavalry that would significantly weaken Custer right before the Little Bighorn. In real life Company B of the 7th Cavalry was assigned to guard the pack train and participated in the Reno-Benteen fight on Reno Hill on June 25-26.
In Little Bighorn (1951) a troop of cavalry racing to the Little Bighorn to warn Custer he is badly out numbered (and thus obviously not part of his column) has a guidon with the letter "C" and no regimental number. Thus they are troop C of some cavalry regiment. If they are troop C of the Seventh Cavalry (which was in Custer's Last Stand in real history) Custer will have one less troop than in real history.
In Warpath (1951) a troop of the Seventh Cavalry suffers heavy casualties in a fight on a river island soon before the Little Bighorn. This fight, like the one in The Plainsman (1936) is obviously inspired by the Beecher Island Fight in 1868. The protagonist serves under a fictional Capt. Gregson, and I think the troop is M, commanded by Captain French in Reno's battalion.
In Bugles in the Afternoon (1952) a troop of the Seventh Cavalry suffers heavy casualties - in a fight obviously inspired by the Wagon Box Fight in 1867 - soon before the Little Bighorn. The protagonist is a member of a troop commanded by Myles Moylan, who commanded troop A, which was in Reno's battalion, in real history.
In The Command (1954) the southern Pains tribes turn hostile after hearing of Custer's Last Stand. Company D of the 2nd or 7th Cavalry - I couldn't hear - is involved in the southern plains. Company D of the 7th Cavalry, commanded by Capt. Weir, was in Benteen's battalion.
So in any fictional universe that includes The Plainsman (1936), Little Bighorn (1951), Warpath (1951), Bugles in the Afternoon (1952), & The Command (1954) 2 of 12 twelve companies of the Seventh Cavalry that were in the Little Bighorn campaign in real life would have suffered heavy casualties soon before the campaign began, and up to 3 others may have suffered heavy casualties or been detached for other duties and not with Custer's command.
So in a wild west movie universe including those movies the Seventh Cavalry would have been much weaker at the Little Bighorn than it was in real life, and thus the 5 movies can be thought of as unintentionally providing a fictional explanation for Custer's defeat that isn't valid in real life.