Christopher Nolan refused to use CGI to add soldiers to the beach for Dunkirk. The end result looks like more of a beach outing than 100k+ soldiers desperate to evacuate.
Christopher Nolan is a notable hold out who never uses CGI though, so this is a pretty extreme & rare example.
Wait, not even Inception? This is crazy
Months of set work to fold that road. I heard they are still rebuilding parts of Paris to this day.
Famously, Waterloo (1970) used 17,000 Soviet Union soldiers and (Cold War-era) cavalry brigade as extras.
They also drilled, slept, and fought like real 1815 infantrymen and cavalrymen, as it was.