One of the characteristics of World War I was the Trench warfare which shows one of those cases when defender has a large advantage over the attacker:
(..) a revolution in firepower was not matched by similar advances in mobility, resulting in a grueling form of warfare in which the defender held the advantage.
To me, the defender having such a great advantage over the attacker sounds more of an exception rather than something common. Some examples which emphasize attacker's advantage:
- cyberwarfare where it is the attacker that has an advantage
- rockets were developed way before the anti-ballistic missiles were developed
I am interested in examples of conflicts where warfare technology enabled the defender a significant advantage over the attacker.