Abattis, military pits, caltrops and spikes, stuck through planks, and explosive machines were employed in front of different parts of the defences.

Mines were resorted to in front of the Flag-staff Bastion to retard the French approaches.

They were made in rocky soil with craters from twelve to fifteen feet deep.

The Russian counter-approaches generally consisted of fleches, united by a simple trench.
Captain McClelland, one of our officers sent to the Crimea, from whose valuable Report most of the foregoing details are gathered, adds the following remarks upon these works of defence:-- "From the preceding hasty and imperfect account of the defences of Sebastopol, it will appear how little foundation there was for the generally-received accounts of the stupendous dimensions of the works, and of new systems of fortifications brought into play.

The plain truth is, that these defences were simple temporary fortifications of rather greater dimensions than usual, and that not a single new principle of engineering was developed.