"Suppose they marched up to our mines with a numerous army, how could they subsist for want of provision."——Moyle, Diss. on the Rev. of Athens.
"If they foraged in small parties."——Same.
The sense is future, and therefore should march, should forage, would have been more correct.
"I should not act the part of an impartial spectator, if I dedicated the following papers to one who is not of the most consummate and acknowleged merit."——Spect. Dedic.
If I should dedicate, would have been more accurate.
A similar fault occurs in the following passage.
"If nature thunder'd in his opening ears,
And stunn'd him with the music of the spheres."
Pope, Essay on Man.
If nature should thunder and stun him, is the meaning.
There is another article that deserves to be mentioned; which is, the use of a verb after as or than, apparently without a nominative.