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:

I am interested in examples of conflicts where warfare technology enabled the defender a significant advantage over the attacker.

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    I'd posture that city walls were a huge advantage for many centuries. Oct 5, 2021 at 13:28
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    The US Civil War seems an obvious example. The US lost more men in that war than in all its other military actions in its history combined.
    – T.E.D.
    Oct 5, 2021 at 13:35
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    Your question does not have an authoritative answer; can you revise the question to have an authoritative answer?
    – MCW
    Oct 5, 2021 at 14:00
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    @Alexei, H:SE is based on the assumption that every question has a single, authoritative answer that can be objectively identified. That doesn't mean that questions without an authoritative answer are "bad", it just means they don't belong here. The internet has plenty of places to discuss questions that don't fit here, and list questions belong in those places. I clarified the meta-answer in response to your comment; thank you.
    – MCW
    Oct 5, 2021 at 14:51
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    Incidentally, there are StackExchange sites which allow "big-list" questions, where instead of a single authoritative answer, one gets a "big list" of answers. History of Science and Mathematics Stack Exchange (hsm.stackexchange.com) is one of these. Make sure, you use the "big-list" as one of the tags. Oct 5, 2021 at 17:31

2 Answers 2


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.

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    The US radar proximity fuze was developed between 1940 and 1942, with first shoot-down in the Solomons in January of 1943. To fit in a 5" shell takes a pretty small radar unit.
    – Jon Custer
    Oct 5, 2021 at 15:10
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    @JonCuster True, but the radar in an AA shell only needs to detect things within a few yards, not tens of miles.
    – Ryan_L
    Oct 5, 2021 at 16:39
  • @Ryan_L - getting fired from a gun adds some additional engineering issues as well...
    – Jon Custer
    Oct 5, 2021 at 16:41

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.

  • Even cheaper - a spade
    – mmmmmm
    Oct 7, 2021 at 15:57
  • yeah, a spade to move earth to protect yourself
    – James
    Oct 7, 2021 at 17:19

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