i won't attack at all, be a tactician dude! just lay seige until they starve (unlikely) or salley forth. when they salley put your skirmishers to harrass them as they walk twards your mass of hastati. when they get close hastati throw pila and run. enemy follow. during this time your general cavalry is inching around the flank of the hoplites. send one to engage and chase away there general and the restr to attack them in the back. the moment the lines are fractured charge in all infantry, even depleted velites and overwhelm them.
thats how i'd do it.
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