The Period

A period is used to mark the end of a sentence that makes a statement:

The CF must be capable of delivering sophisticated military operations to protect Canadians at home and abroad..

A period, not an exclamation point, is the best choice at the end of a sentence that makes a mild command:

Present your weapons.

A period, not a question mark, ends a sentence that poses an indirect question—that reports a question someone has asked or merely ponders:

One wonders if senior officers have made note of the two-sided nature of the military relationship and their obligation to tell their political masters truths that they may not want to hear.

Periods are also used in abbreviations (though see the comment below). Familiar Latin abbreviations found in academic writing always appear with periods:

cf.   et al.   e.g.   etc.   ibid.   i.e.   n.b.   op. cit.   viz.

If a sentence ends with an abbreviation that takes a period, that period also serves as the punctuation for the sentence. Do not add a second period.

Militaries must insure that their personnel are properly motivated to achieve mission objectives by, for example, recruiting quality candidates, ensuring quality of life, espousing noble military values, offering challenge, etc.

There is a tendency to omit the period in abbreviations used in military writing, such as acronyms (words made up of initial letters in a phrase or title), initialisms (formed from the initial letters in a series of words but not pronounceable), suspensions (a form of abbreviation in which middle letters in a word are dropped), and abbreviations proper (wherein a period takes the place of omitted letters).