ANCIENT INVASIONS OF INDIA. 527 



We have been careful to mention these numerous 

 technical details, because of the importance of the Indus 

 as a line of defence to North Western India an invader 

 entering the British Empire in this direction being always 

 liable (should he succeed in crossing the river) to be cut 

 off from his line of communication, without warning and 

 for an indefinite period of time, by a sudden flood. 

 Nevertheless the neighbourhood of Attock, and down 

 towards Kalabagh, " has seen the passage of every 

 conqueror who has invaded India from the north 

 west, from the time of Alexander the Great down- 

 wards." * 



This is quite true: and that being so, perhaps we 

 shall be pardoned if we venture upon a short digres- 

 sion, upon a point of great military and historical in- 

 terest (which has been much debated of late years, 

 and has given rise to many differences of opinion) in 

 order to put the matter in what we conceive to be its 

 proper light before the reader. We desire however 

 to premise our remarks on this subject by stating that 

 it is an axiom of military science that rivers as a rule make a 

 bad frontier, strategically speaking, being incapable of 

 stopping the advance of a well-led and energetic enemy. 

 There is however no rule without an exception; and 

 we have here to deal with a river of very exceptional 

 character. 



The principal invasions of India by foreign conquerors 

 from the north west were three in number. First by 

 Alexander the Great, who entered India early in B.C. 327. 

 He crossed the Indus above Attock, and advanced 



* Murray's Handbook for India & Ceylon, 1892, Route 13, 

 p. 210. 



