venture to ask the hospitality of your columns for an adequate
discussion of the gallant officer's second question, as to the binding
force attributable to international law. Upon this I may, however,
perhaps venture to refer him to some brief remarks, addressed to you a
good many years ago, and now to be found at pp. 101 and 105 of the new
edition of my "Letters to _The Times_ upon War and Neutrality
(1881-1918)."

I am, Sir, your obedient servant,
T. E. HOLLAND.
Oxford, April 24 (1914).

ATTACK FROM THE AIR

THE RULES OF INTERNATIONAL LAW

Sir,--In reply to Colonel Jackson's inquiry as to any rule of
international law bearing upon aerial attack upon London, I referred him
to the, now generally accepted, prohibition of the "bombardment, _by any
means whatever_, of towns, &c., which are not defended." This rule has
been growing into its present form ever since the Brussels Conference of
1874. The words italicised were added to it in 1907, to show that it
applies to the action of _aeronefs_ as well as to that of land
batteries. It clearly prohibits any wanton bombardment, undertaken with
no distinctly military object in view, and the prohibition is much more
sweeping, for reasons not far to seek, than that imposed by Convention
No. ix. of 1907 upon the treatment of coast towns by hostile fleets.

So far good; but further questions arise, as to which no diplomatically
authoritative answers are as yet available; and I, for one, am not wise
above that which is written. One asks, for instance, what places are
_prima facie_ "undefended." Can a "great centre of population" claim
this character, although it contains barracks, stores, and bodies of
troops? For the affirmative I can vouch only the authority of the
Institut de Droit International, which in 1896, in the course of the
discussion of a draft prepared by General Den Beer Pourtugael and
myself, adopted a statement to that effect. A different view seems to be
taken in the German _Kriegsbrauch_, p. 22. One also asks: Under what
circumstances does a place, _prima facie_, "undefended," cease to
possess that character? Doubtless so soon as access to it is forcibly
denied to the land forces of the enemy; hardly, to borrow an
illustration from Colonel Jackson's letter of Thursday last, should the
place merely decline to submit to the dictation of two men in an
aeroplane.

I read with great pleasure the colonel's warning, addressed to the
United Service Institution,