A Military Writer's Handbook
Punctuation

The Exclamation Point

American writer F. Scott Fitzgerald once remarked that using an exclamation point "is like laughing at your own joke." The best practice is to use the exclamation point sparingly, if at all. In good writing, the exclamation point is seldom used to emphasize a point or to express amazement, surprise, or other emotions. Rather, let the force of your words convey the intended meaning.

Limit use of the exclamation point to emphatic statements or strong commands. When used, exclamation marks appear most often in quoted speech to indicate emotion.

"Good God! Did we send men to fight in that?" -LtGen Kiggel at Passchendaele
"Troops, at attention!"

In formal writing, the practice is to avoid using exclamation points altogether, except perhaps with an interjection. Rather, use appropriate language to create emphasis or tone in the sentence: words such as "surprisingly" or "amazingly," for example. The second sample sentence sounds much more professional than the sentence above it.

The US continues to act without UN sanction in Iraq!
Surprisingly, the US continues to act without UN sanction in Iraq.
Incredible! Do you expect me to believe that?