Calling all armchair generals! Boudica's Last Stand.

[Renatus]

Tacitus states that... only when he was reinforced did he decide to give battle....

Just to be annoyingly accurate - Tacitus doesn't state that! ;-)

Suetonius had the fourteenth legion with the veterans of the twentieth, and auxiliaries from the neighbourhood, to the number of about ten thousand armed men, when he prepared to break off delay and fight a battle (Annals, 14.34). That's all - no mention of reinforcements gained or awaited, or explanation for the 'delay'. As Michael has said, it's probable that he was waiting for more men, but not certain.

This translation does not take account of the word with which Tacitus begins the passage, "iam". This means literally "at that (or this) time", which would seem to suggest that the situation had changed. Moreover, Tacitus goes on to refer to the auxiliaries "[e] proximis", 'from the nearest (forts)', which by definition would not have been with him in London. Therefore, although Tacitus does not say specifically that Paulinus had been reinforced, the implication is pretty clear.