What is the impact of science and technology on the military?

Huge! (Oooh I hate that non-word "technology!) Science and Engineering give the Armed Services better:

weapons,

anti-attack detection and defences,

communications,

transport,

battlefield clothing, food, etc.,

medical help,

...

One effect of advances in equipment is that in some areas at least, particularly naval warfare, fewer personnel are needed to participate in the fighting, so be exposed to the very real danger of being killed. Although a navy always describes itself as sinking its enemy's ships and submarines, these vessels contain many men who are likely to be drowned with it. Reduce the manpower and you reduce the number of deaths.

Another is that it is possible to replace blanket bombing of an area with a few, more accurate missiles - but neither weapon is a justification for throwing it at residential areas, and the unforunate corollary is that when used against insurgents that is precisely what happens.