What's the highest rank in the military and how do I achieve it?

General of the Armies is the highest military rank and it has been held by only two individuals; George Washington and Blackjack Pershing. That rank however is unlikely to ever be awarded again, so the next highest is General of the Army. This rank is only awarded during wartime, the last person to hold it was Omar Bradley. For all practical purposes, the third highest rank, General, is as high as a person can get promoted. Attend a military academy, spend thirty years in the Army, see combat and survive, advance your military education and you might stand a chance.

In the Army, that would be General of the Armies. There have only ever been two, and one was appointed such almost 200 years after he died. The Naval equivalent is the Admiral of the Navy; there has only ever been one, and the rank was disestablished with his death. Somewhat more common, although there are none today, are Fleet Admirals and Generals of the Army. There were four and five of those, respectively, and one was converted to a General of the Air Force. It is highly unlikely that these five-star ranks would be revived outside a major war. The highest rank currently attainable is O-10, the four-star general or admiral.

One does not "rank up" in the military. One is promoted. Let's look at a four-star general's career to see how one might be promoted to this rank. In addition to the various commands he has held, he was a distinguished honor graduate at USMA, earned an MPA and PhD from Princeton, was a top graduate from the Command and General Staff College, and has a number of badges and a Ranger tab.

We call it getting promoted as opposed to "rank up". Starting as a Private and ending as a Colonel is very admirable and back during WWI and WWII it was very common for Battlefield Commissions to be awarded whereas University was not required. Here's the rank structure of the US Military:

Army/Marines/Air Force Navy

2nd Lieutenant Ensign

1st Lieutenant Lieutenant Junior Grade

Captain Lieutenant

Major Lieutenant Commander

Lieutenant Colonel Commander

Colonel Captain

Brigadier General (1-star) Rear Admiral Lower Half (1-star)

Major General (2-star) Rear Admiral Upper Half

Lieutenant General (3-star) Vice Admiral

General (4-star) Admiral

General of the Armies (unofficially six xtars)is an Honorary title given to George Washington, so that he will ALWAYS be the highest ranking officer.

General of Army, Air Force, Fleet Adm. (five stars) war time rank only.

General (four stars) is the highest currently, by law the Chairman of Joint Chiefs is the highest ranking officer in the Military.

Commander in Chief, IS NOT a military rank. It is a title.

The rank of General is the highest rank in the US Army. Fleet Admiral in the US Navy (need a major war to achieve this, otherwise just Admiral). General of the Air Forces ... for you guessed it the Air Force (USA).

You earn ranks from having skills, intelligence, attending training, loyalty, hard work, commitment, serving with honour, field skills (experience), etc etc ... as with most career advancements (just in a military sense).

Not sure on the other branchs, but in the army it is General of the Army of which there is only one such position, it has 5 stars. It is used only in wartime ( declared ) , the last being Omar Bradley back in 1950. There is still on the books a General of the Armies which has only been used twice since its inception in the late 1700's. It is largely symbolic now that the military has become 3 distinct branchs now , with the marines still a part of the Dept. of the Navy.

You would need to do 20-40 years of service to get into the command level ranks.

Highest Rank -Commander in Cheif- President of the United States, controls the strongest military in the history of man, you can achive this by gaining political popularity and running for office.

Ranking up -Knowledge, the U.S. Army *Wants smart soliders thats why they give you money to go to college and its required to rank up, you're givin three(3) chances to rank up if u deny all three of them they'll simply say "thank you for your service, you may go home".

Commander in Chief (run for Office)

5 star General (be extremely smart and lucky)

two issues with what you said (not saying he was lying just sounds odd) if he had retired as a corpral (although you didn't really say he retired) than that was VERY low for someone who was in for 20 some years. but a Colonel is right below general which if he hadn't gone to school ( or officer training of some sort) that sounds damn near impossible.