Usually 20, unless you're forced into early retirement for various reasons (such as a reduction in force strength, like what occurred after the end of the Cold War).
Retirement is available after 20 years of service.
That depends on the military force and often the terms of your employment.
20 or more years.
22
6 years
Social Security Number
You can't retire after only 4 years.
Like all military personnel in the US, they can retire from military service after there first enlistment is over. The standard enlistment is 4 years, but sometimes the first one can be 6 years depending on the branch/career chosen. For the Marines it's generally 4 years. Military Service men and women can re-enlist and if they stay in the Military for 20 years earn a full government pension.
I believe it was 25 or 30 years, after which they could retire and have a wife and family.
Until you reach sixty years of age?
40
join the military or some other organization and stay there for 20 years, you can really retire anywhere after 20 years otherwise invest in an IRA and put money away every check, or invest in 401k and stock at other jobs.
40
40
40
Around 1613, three years before his death.