86. Tactics Derived from Results of Experience, 172 87. Todleben’s Rules, 173 88. The Attack, 173 89. The Defence, 174 90. Advantage Lies with Besieger, 176 BREACHING BY MINES. 91. Preparation of Wall Location and Size of Charge, 176 92. Galleries behind Counter-scarps, 177 93. Galleries through Scarp, 177 CHAPTER IV. BLASTING AND DEMOLITIONS. 94-97. Definitions; Tools and Appliances, 178 98. Tamping Blasts, 179 99. Determining the Charge, 179 100. Precautions, 180 DEMOLITIONS. 101. Deliberate Demolitions, 180 102. Hasty Demolitions, 181 103. Houses and Magazines, 181 104. Walls, 181 105. Stockades, 182 106. Bridges, 182 107. Tunnels, Canal-locks, etc., 183 108. Railroads, 183 109. Rolling-stock, 184 110. Excess of Explosive to be Used, 184 ATTACK OF FORTIFIED PLACES. CHAPTER I. THE ATTACK WITHOUT THE USE OF REGULAR APPROACHES. =1.= A fortified position may be taken by _blockade_, _surprise_, _assault_, _bombardment_, or _siege_. A =blockade= consists in so surrounding a place and closing its communications as to keep the garrison from receiving reinforcements, provisions, and supplies sufficient to enable it to continue the defence and to avoid starvation. The object of the attacking force is, in general, to completely close all communications between the garrison and the exterior; but this is not always possible, nor is it necessary in all cases, since such obstruction of communications as will reduce the incoming supplies below the necessary expenditures of the garrison will ultimately exhaust its stores. An efficient blockade, continued long enough, will consequently reduce any place.