What is the word for ditches used as a military defense?

i don't really know the circumstances. i personally think not due to it not being fair for all parties and how hated i'd become if i thought it was a good thing.

answer; (d) i believe the best answer is ; ///people said that man could not fly, but in 1903, orville and wilbur wright made the first sustained powered flight in a heavier- than-air machine;