Are there any modern history examples of large scale conflicts where warfare technology provides a great advantage to the defender, except WWI? [closed]

Question

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.

Answer 1

Obvious example. Radar.

First radars during WWII were too heavy and had a short operational range. Hence, only the defender had the option of installing a radar to concentrate forces and defend certain places, the attacker didn't have the same alternative.

During the Battle of Britain, the United Kingdom was capable of detecting German planes over the channel, giving UK pilots enough time to concentrate and reach altitude (that's an advantage in air battle).

Radar had the same effect in the Battle of the Atlantic, once the radar was small enough, the UK put several of them in ships, so they were able to detect German submarines when they were on the surface (most submarine attacks were on the surface). The Germans lost several submarines without knowing that British had radars on their ships.

Answer 2

the defender having such a great advantage over the attacker sounds more of an exception

This is a completely wrong concept. Every war expert will tell you that defending is always more cheaply done, in human lives and means used. This is no different today than it was in Antiquity or during the Middle Ages.

Since you ask for technology that gives the defender an advantage, I'll give a very plain example to reinforce the cheaply idea: concrete cement.