These  are  the  most  natural  dispositions,  but  they
may  be  modified  in  many  ways ;  for  example,  D  and
E  may  join  A,  and  form  a  first  line,  the  other  joining
B,  and  forming  a  second  line.  Three  corps  may  be
put  in  the  first  line,  and  two  in  the  second ;  or,  two
in  the  first  and  three  in  the  second,  &c.  This  will


160  PKEKCIPLES    OF    STRATEGY.
depend  on  the  ulterior  designs  of  the  general,  and  the
relative  facilities  offered  by  distances  and  the  ground
of  bringing  up  one  or  the  other  corps  to  the  support
of  the  advanced  guard ;  or  he  may  be  influenced  by
some  other  of  the  many  circumstances  which  are  con
stantly  arising  to  interfere  with  what  would  be
invariable  rules  in  war.  There  is  one  great  advan
tage  in  this,  for  the  enemy  cannot  know,  until  the  last
moment,  the  disposition  of  the  troops  he  is  to  contend


against.
If  the  enemy  shows  himself  in  force  in  such  a  posi
tion  as  to  threaten  the  flank  of  the  army,  all  the  corps
change  direction  towards  that  side,  and  it  will  be  seen
that  the  general  arrangement  remains  unchanged.
There  is  still  an  advanced  corps,  a  reserve,  a  central
corps,  and  one  on  each  flank.  Suppose,  for  example
(fig.  11),  the  army  to  have  changed  direction  to  the
right :  D  forms  the  advanced  guard,  B  remains  in  the
centre,  A  and  C  are  on  the  flanks,  and  E  is  the
reserve.  In  retreat,  or  to  attack  an  enemy  who  is  in
the  rear,  the  arrangement  is  the  same.
