The Lost Fleet (Jack Campbell)

This has probably the best space battles I have read.  They involve massive battles (200+ ships on a side) but ships and crews are characterised well so you wince when a battleship goes down.

DELTA VEE & RELATIVITY
Fights are characterised by management of velocity and vector. Ships can accelerate up to .2 light, the fastest speed at which combat is practical.  Beyond that, relativity kicks in; basically ships are moving so fast you are seeing the ship where it was... some time ago. At such speed, computers do all the targeting and humans just press the 'fire' button.

Fights are won by predicting where any enemy will be; as the enemy, unless moving slowly or at very short range, is not where he appears to be.  When ships 'jump' into a system, sometimes defenders do not realise they are there for many hours; the time it takes for the light reflecting from the attackers' ships to arrive at the defender. 

Warp gates provide convenient chokepoints for battles as otherwise ships could simply accelerate away above .2 light and avoid battle.


This dude is also into relativity. He is also smart - I mean, could YOU have pulled the ladies with that hairdo?

THE TECH
Ships have missiles, and lasers. However the most interesting weapons are the 'grape launchers'. These railguns can carry solid kinetic rounds for bombardment, or more commonly, fire a spray of tiny ball bearings into wide arcs. 

Ships usually launch missiles from longer range, spray huge fields of 'grapeshot' to defeat enemy missiles or overload shields, and then finish ships off with lasers. 

THE STORYLINE
Basically, a heroic captain is awakened from cyro-sleep and finds himself in charge of a fleet (by reason of his 100 years seniority). Due to the high attrition of crews in the war, and the near-suicidal tactics developed over the 100 years, his experience and tactics are unparallelled.  He leads his fleet  - which is stranded deep behind enemy lines, dozens of 'jumps' from home - in an odyessy which will cover much of the known galaxy.

The writing is solid but unspectacular (the personal scenes are a bit clumsy), but the battles and tactics are interesting and strung together in an engaging manner, and the author (a navy officer himself) has a good grasp of military life. 

This is series the best spaceship sci fi out there, and the series (which started with 'Dauntless') has been rebooted with a new book recently...