With so much of movement through space being dependent on gravitational forces, I'd imagine the FIRST era of space battles being fairly bleek and fatalistic...much like WWI, where waves of men went charging to their death because technology outpaced current warfare tactics. I imagine two sides launching missles at eachother from hundres of thousands of km away, with both sides making no attempt to change their trajectory, praying to the space gods that the other side's weapons failed or were inaccurate.
Lets say you have a ship going from earth to...Jupiter. Your flight course would be a rigid window because other planetary bodies will be pushing and pulling you in different directions.. Altering your ship's course would alter your ability to reach your intended destination. Moving out of the way of a weapon or slowing down might slingshot you out of an orbit, or pull you into another. Such gravitational forces would need serious power to counteract. Would a ship carry enough resources to do this?
I'm thinking of it similar to naval battles where large ships take immense power to change their direction or speed. A large ship can only turn so fast, and even then it's a fairly slow correction. Torpedos fired undetected or from a close enough distance with consideration to target's speed and direction could make maneuvering futile. Space battle could have similar problems to deal with. Can you detect a missle before it hits you? Could you change direction to avoid it without putting your trajectory at risk? Do you have the power and resources to do it at all?
If someone decided to use LASERS PEW PEW!, any space travel would be signing your own death warrant.