‘As long as necessary,’ Cato replied, ‘until we are relieved, or the enemy gives up their attempt to take the fort.’

Severus gave a mirthless laugh. ‘We aren’t going to be relieved. The fort is too far from any help.’

‘Not true,’ Macro chided his subordinate. ‘As soon as there’s enough light, we can put a flame to the signal fire. If the weather is good, the smoke will be seen from Gobannium. They’ll raise the alarm and Legate Quintatus will send out a column. You’ll see.’

‘We can’t use the signal fire,’ said Cato.

Macro frowned. ‘Why not?’

‘Think about it. As far as Quintatus knows, the enemy is several days’ march to the north, close to Ostorius and his army. Once the smoke from our signal fire is spotted and reported to him, he’ll send out a relief column all right, and it’ll march straight into a trap. Caratacus will pick his ground carefully and he has more than enough men to annihilate a detached force from the Fourteenth.’ Cato shrugged. ‘We daren’t light the fire and lure our comrades to their deaths. Better that we fight it out, or find some way of getting a message through to the legate before he sends us any help.’ As he concluded, Cato felt a sudden cold stab of horror. ‘Shit . . .’

Macro cocked an eyebrow anxiously. ‘What is it, sir?’

‘The reinforcement column. They may already be on the road to Bruccium. If they arrive while Caratacus is still here . . .’

Every man in the room understood the danger well enough, and it was Macro who spoke up first. ‘If they see the smoke from the alarm beacon, they’ll know we’re under attack and turn back.’

‘Assuming the sky remains clear enough for them to see it.’

Macro pursed his lips. ‘Either way, we have to warn them, sir. We have to get a message to the legate.’

‘How?’ asked Cato. ‘Even now, I suspect that Caratacus has already closed the noose around us. It’d be a brave man who dared to try and find his way through the enemy lines. I’ll not send a man to certain death.’

‘Even if he volunteers?’ Severus asked hopefully.

‘Even if he is volunteered.’

Macro shook his head. ‘Sir, it’s a risk we have to take. Not just to save our necks. Ostorius needs to know what the situation is. If he learns that Caratacus and his army are here then he can march on Bruccium at once. It’s the opportunity he’s been waiting for. The chance to catch and destroy the enemy once and for all.’