This is going to share the podium of worst novel about the Second Punic War that I've read with Ross Leckie's trilogy. The flaws are so many I can't possibly go about each individually, so I'll group them:
1. The language is too modern. Really, really too modern. It's especially distracting during dialogue passages, because of how non-authentic it sounds because of the language. The characters, both protagonist and secondary, speak like people today at any informal gathering, with no attempt at standard English or formality/politeness.
I don't expect novels to be written resembling Olde English to give the impression of classicity, it's too tricky a technique. However, there should be an attempt to write using a vocabulary and a style as standard as possible, taking care not to let your regional speech seep through and not sound slangy or idiomatic. American authors are particularly prone to stumble over this stone, and should therefore be more careful.
2. Piggybacking on the above, the manner in which people interact and relate to each other, both between peers and across social classes, is also lacking in "period authenticity" and truthfulness to history. The Romans weren't like us modern peoples, so over-familiar, so ready to fake smiles, so informal, so unmindful of rank and class and ceremony. There's such a marked carefree and unceremonious atmosphere that you wonder what happened to the Roman concepts of dignitas and auctoritas amongst senators and patricians. I was almost expecting characters to greet each other with What's up, mate? instead of that curious attempt at sounding "Roman" by inserting a salutatio formula incorrectly.
An example of this that did me in was the author making Gaius Laelius, sidekick and lifelong friend of Scipio the son, call him Scippy. I mean . . . what? Scippy?!
But what's the point of that? And can you imagine friends calling Cato or Fabius Maximus by diminutives like this? Or Sulla, Caesar, Augustus, etc., be called something like Luce, Juls, Gus by their friends? "Hey, Porty, drop your oxen now, clean the dirt from under your nails, and let's go to the Rostra!"
3. The author doesn't seem to know how to handle the narrative and steer it along a defined arc. Instead, he seems to write like checking historical facts boxes and inserting superfluous and poorly done sex scenes when he doesn't know what to write in-between one check box and the next. Hannibal swears to his dad to destroy Rome, check. The Barcas conquer Hispania, check. Cato and Fabius Maximus meet and scheme, check. Hannibal crosses the Alps, check. Scipio is defeated at Ticinus, check. Battle of Trebia, check. Slaughter at Cannae, check. Oh, and why don't I write a scene of Scipio Jr having sex with his slave at the beginning, and then again banging a horny Italian young matron in-between battles? I mean, what else can be used as filler while awaiting the next big battle?
4. Since the author doesn't have a story but follows History instead, his plot becomes didactic and ridiculously linear. He inserts maps in each chapter where a battle is happening. I'm not joking, he really does. There you are reading the description of a battle between Romans and Carthaginians and . . . poof! A map appears right in the middle and breaks immersion. What is this? A novel or a non-fiction book? In what well-made and respectable Historical Fiction novel is it acceptable to insert battle maps in the middle of chapters?
And since we're into unnecessary didacticism, why is this author including quotation reference numbers? Whenever Tessmer includes a word-for-word quote by a real historical figure, he adds an endnote number that leads to the source it was taken from. Sorry, again, what is this? A novel or a non-fiction book? Make up your mind, please. It can't be both.
5. Manichaean characterisation. Yes, I'm perfectly aware of the existence of rival factions in the Roman Senate (though I disagree with the authorial choice to call each faction the Latin and Greek parties respectively since it doesn't reflect the historical reality, I can accept that it's a creative licence as per the Author's Note), but that doesn't mean the existence of such a rivalry is a green light for writing black-and-white goodies and baddies depending on your personal sympathies. The characterisation of Quintus Fabius Maximus as a mustache-twirling cartoon villain (forget it that Romans had no mustache to twirl) is frankly unacceptable to me. And no, I'm no admirer of Cunctator, he had his flaws and was a pain in the nether regions, but do give credit where credit is due: he had his part in Rome's final victory. And Cato? A bigger pain in the nether regions, if that's possible, but he was no close-minded mulish bumbler as he's portrayed here.
The point is: don't exaggerate. It's possible to write antagonist characters without having them resemble Snidely Whiplash. Nor do you need to demean the others to elevate your protagonist/hero.
6. The editing is terrible. Entire paragraphs are underlined. It should've undergone a bit of editing before it was published, because the typos and formatting don't give a good impression.
And there are also other issues and inaccuracies I found, but the ones listed here should suffice to give potential readers a good idea of whether this book would be for them or not. For me, it wasn't.