Gods of War by Jack Ludlow
Lucius Falerius is dead, and Rome in its entirety mourns the passing of its most powerful senator. It falls to his young son Marcellus to carry out his father's legacy and restore the rights promised to the defeated Sicilian slaves, yet there are those who will not see the honour of Rome compromised and the slaves assuaged. On the Roman border provinces there is trouble, and the legions move north to neutralise the threat posed by the Celts. The confederation of Celtic tribes is united under one Chieftain, the formidable and unpredictable Brennos, yet there is a plot to see him dead and the confederation broken. For Brennos, the treachery comes from within his own family, for which he will exact a brutal and bloody revenge.