Let's look at the three tiers of officers: General Officers, Field Officers, and Company Officers.
In the General Officers, we have: General, Lieutenant General, Major General, and Brigadier General.
A Major General historically called Sergeant Major General.
The Brigadier General has a nice history. The term "Brigadier" in French Military is equivalent to "Corporal", hence the titles:
Captain General, Lieutenant General, Sergeant General, and Corporal General as a generalization.
In the Field Officers, we have: Colonel, Lieutenant Colonel, and Major.
Major was historically called Sergeant Major. Hence, the titles:
Captain Colonel, Lieutenant Colonel, and Sergeant Colonel. Thus, Corporal Colonel is a missing rank.
|Category||Main (Mainguard)||Vice (Vanguard)||Rear Upper (Rearguard Right)||Rear Lower (Rearguard Left)|
|General (Stars) Officers||Captain General|
|Flag (Stars) Officers||Admiral|
|Read Admiral (Upper Half)|
Read Admiral (Upper Half)
|Rear Admiral (Lower Half)|
Rear Admiral (Lower Half)
|Field (Eagle and Flower) Officers||Captain Colonel|
|Naval Field (Eagle and Flower) Officers||Commodore|
|Rear Commodore (Upper Half)|
|Rear Commodore (Lower Half)|
|Company (Bars) Officers||Captain|
|Ship (Bars) Officers||Captain|
Lieutenant Junior Grade
|Rear Captain (Upper Half)|
Chief Petty Officer
|Rear Captain (Lower Half)|
|Military Fantasy Low Rank Naval Officers||Commander||Vice Commander||Rear Commander (Upper Half)||Rear Commander (Lower Half)|
|3 Major Rank by 4 Minor Ranks|
4 Major Ranks by 3 Minor Ranks
|Lieutenant General||Vice Admiral|
|Sergeant General||Rear Admiral|
|Captain Colonel||Vice Commodore|
|Lieutenant Colonel||Rear Commodore|
|Corporal Colonel||Vice Captain|
|3||Mainguard, Vanguard, Rearguard|
[Main/Chief/Full] General, Vice/Front-line/Vanguard/Lieutenant General, Rear/Rearguard General
|4||Mainguard, Vanguard, Rearguard Right, Rearguard Left|
|5||Mainguard, Vanguard, Rearguard, Right Wing, Left Wing|
[Main/Chief/Full] General, Vice/Front-line/Vanguard/Lieutenant General, Rear/Rearguard General, Right [Wing] General, Left [Wing] General
|6||Mainguard, Vanguard, Rearguard Right, Rearguard Left, Right Wing, Left Wing|
|7||Mainguard, Vanguard, Rearguard, Right Wing, Left Wing, Right Flank, Left Flank|
|8||Mainguard, Vanguard, Rearguard Right, Rearguard Left, Right Wing, Left Wing, Right Flank, Left Flank|
|9||Mainguard, Vanguard, Rearguard, Rearguard Right, Rearguard Left, Right Wing, Left Wing, Right Flank, Left Flank|
The splitting into 3 entities, and splitting into 5 entities are well known. They happen to be the standard way of splitting military into parts.
Vanguard fight the front-lines, and act as skirmishers. Their job is not to fight the main battle immediately, but to harass the enemies. Vanguards should never retreat behind Rearguards without a retreat order. After harassing the enemies, they retreat behind the Mainguard until the Main battle.
Mainguards fight the main battle. Hence their name! During the main battle, Mainguards and Vanguards will take turns during lulls of battle. During the switch, each person holds a frontage of one cubit (18 inches), otherwise, they hold a frontage of one yard (36 inches). The switch occurs by forming a shield wall. The second line of soldiers move up to the front lines. Then the worn out first line soldiers fall back to the back of their formation.
Rearguards maintains supply, night watch, and defense. They are to kill any Vanguards that run from battle. Vanguards must regroup between the Mainguards and Rearguards unless a retreat order has been given. Rearguards are the last ones to retreat. They wait for the Vanguards to retreat first, then the Mainguards retreat, and finally, the Rearguards retreat.