Kalkriese is not the Varus battle site ?

[Tiberius Clodius Corvinus]

Hi,
can anybody tell me which Caecina had command at the pontes longi? I find both often confused or had both some functions in gaul or germany?...

1. Gaius Silius Aulus Caecina Largus; Consul in AD 14; († 24) OR
   
2. Aulus Caecina (Severus) Suf.Consul in 1 BC

btw, Tacitus mentions (ann. I, 62?) that Caecina is in fortieth year of mil. service (in AD 15).
My question here: Which time would his military career likely have started? somewhat around 25 of age as junior tribune? So he would possibly be in his late sixties. :?