We use a proper noun to name a special event. Names of special events must be capitalized.
Here are some special events:
Mardi Gras, Homecoming, Prom
the Flood, the Exodus, the Civil War
We also capitalize the names of time periods. Here are some examples of special time periods:
the McCarthy Era, the Middle Ages, the Industrial Revolution
Any special event or historical time period is a proper noun and should be written with a capital letter.
▶Now you try it. Find the special events or time periods in this sentence that should be capitalized: My grandfather was a boy during the great depression, and then he fought in world war II. Did you find a special event and a historical era to capitalize? Good for you!