‘We’ve got something better than bullets,’ Ken answered very quietly.  He laid his hand as he spoke upon one of the big loose boulders which lay in front of him.

‘See here,’ he went on, ’they’ll come right underneath us.  If we could get this rock down on the team, it would probably stampede the mules.  Then before the men have recovered from their confusion, we ought to be able to give them a couple more.  If we could land one on top of the gun itself, it would damage it pretty badly, even if it doesn’t smash the mountings and make it useless.  What do you say?’

’Say—­why that it’s the greatest scheme ever hatched, and I’m with you every time,’ Roy answered, his face glowing with excitement.  ’And, by Jingo,’ he added, ’if we’d picked the spot for bringing it off, we couldn’t have done better.’

This was true enough.  The spot where they were perched was fully sixty feet above the road, and the slope below was next door to perpendicular.  For another thing, the supply of boulders was unlimited.

The one to which Ken had pointed weighed perhaps a quarter of a ton and was shaped rather like a gigantic egg.  He put his weight against it, and found that it rocked, but even so, he could not be quite certain that their combined efforts could start it over the edge.

‘Wait!’ whispered Roy, and turning slipped away into the thick of the trees.  He was back in a minute, carrying a heavy piece of dead timber.

‘This ought to do the trick,’ he said softly.  Ken nodded.

Meantime the Turks below, all unsuspicious of what was brewing, came slowly and steadily along the road.  Slowly, because not only is a 77-millimetre gun with its caisson a heavy weight, but also because the road was merely an apology for one.  It was nothing but a deeply rutted track thick with sand and loose stones.

The men were in charge of a non-commissioned officer, a Turk like themselves, and consequently were taking it very easy, strolling along, smoking and chatting.

Roy drove his stake deep under the big rock, and gave a slight heave.

‘She’ll shift all right,’ he whispered in a tone of quiet satisfaction.

‘All right.  Wait till I give the word,’ said Ken, with his eyes fixed upon the long gray gun which came jogging slowly onwards, its grim muzzle swaying and lurching as the wheels took the ruts in the road.

It seemed a long time before it came opposite.  Then at last Ken gave one word.

‘Now!’

In an instant they were both on their feet, Roy tugging on the lever, Ken bracing all his weight on the big rock.

It moved, it rolled slowly over, seemed to pause a moment on the edge of the bank, then suddenly shot forward.  Ten feet below, it alighted on the slope, rebounded, and at the same time started half a dozen other stones.  In a moment a rock avalanche was roaring down the steep.  The great stone led the way.  In a series of gigantic leaps, each longer than the last, it thundered downwards, at each jump starting fresh tons of the loose shale which covered the bank.