Star Trek used a "transporter" to save money on having to show a shuttle. Ultimately, it wound up being an important part of the setting, but the writers never really put much thought into it. Or rather, they didn't put much thought into what characters would do with it. Fairly regularly, they needed to write a reason for the transporter to be unable to be used in a lot of situations.
In our own role playing scenario, we had a 40k ship with a teleportarium (yeah) that could transport a room of stuff to itself, or to a location, within around 10,000 kilometres. This very immobile teleporter, with a great size to amount of matter transported ratio, was still an extremely powerful tool. So much so that we had to make a rule where we could only use it once per session, lest we use it as a "get out of jail free" card. In the end, that's all we ended up using it for.
Still, without such a limitation, such a teleporter would be a powerful Strategic tool. At its most basic, a bomb could be placed inside the room and delivered instantaneously. Or perhaps a strike team could capture important personnel with very little risk. Or enemy supplies could be teleported to supply one's own troops. And so on. One could teleport ground troops to a random point in space.
In Star Trek, their transporter had less limitations than ours. Theirs could intelligently control who they teleported, with enough accuracy to target a human. Thus, you could transport half the people in a room, or only the ones wearing special badges etc. One would be able to do the above operations with a greater degree of accuracy.
Presumably, with more advanced technology, such a teleporter could become a more powerful weapon. Why teleport an entire human when you could just teleport a portion of their brain? Entire regiments could be wiped out. Or, were ethics involved, you could teleport just the weapons of the enemy, leaving you with a large number of prisoners.
The more and more precise the technology becomes, the less limited its applications. Eventually, the only real limits are your imagination and counter-measures your opponent would deploy. Warfare would be based around the technical limitations of teleporter technology.
The first teleporter technology may only work on energy. However, once it starts working on matter, it becomes a massive strategic solution. In my fiction for RTS game, they required a device at both ends, and an active series of connecting devices (usually satellites). Even then, the hypothesis was that this entirely killed the shipping lanes. Cities and towns would be centred around these giant devices, as they would be a major source of supplies.
The form of transporter that can take something and push it elsewhere without requiring a receiving end would be very far off. The first advances would be in miniaturisation and efficiency, making the devices more accessible. Any war that occurred would have to take such devices into account, perhaps controlling the devices through some esoteric form of hacking or blasting an area with radiation.
After rambling for a bit, this I realised that the scope of this is insane, so I'm cutting this short. Sorry, I'll touch on this later.