Could you be thinking of Timothy Zahn's Conquerors trilogy?
It dates from 1994; the first book deals with a race of aliens attacking a human empire; while the second book is mainly told from the perspective of the aliens.
If it serves to jog your memory further, the aliens have ships that seem to be almost indestructible, and have much faster communications thanks to their Elders.
There's a much better summary of the first novel on Amazon:
Timothy Zahn, Hugo Award-winning author of The New York Times best-selling Star Wars trilogy, blazes a spectacular new path across the sky in an epic original novel of star-spanning action adventure, mystery and intrigue. A long era of peace and prosperity in the interstellar Commonwealth has suddenly come to an end. Four alien starships of unknown origin have attacked, without provocation, an eight-ship Peacemaker task force, utterly destroying it in six savage minutes. The authorities claim there were no survivors. But Lord Stewart Cavanaugh, a former member of Parliament, has learned through back channels that one man may have survived to be captured by the aliens: his son, Commander Pheylan Cavanaugh. A large-scale invasion appears imminent, and the strictest security measures are in effect . . . measures that Lord Cavanaugh has no choice but to defy. He recruits Adam Quinn, who once flew with the elite Copperheads--fighter pilots whose minds are literally one with their machines--to rescue his son. Quinn assembles a crack force of Copperheads to steal out of the Commonwealth security zone and snatch Pheylan Cavanaugh from the conquerors. Depending on the outcome, Quinn and his men will retum home as heroes or as the galaxy's most despised traitors--if they come home at all.