The consul Lævinus is said to have dealt in the same way with some spies that were taken, and so did Xerxes by some Greek detectives. At the famous siege of Antwerp in 1584-5, when a Brabant spy was brought before the Prince of Parma, the latter gave orders that he should be shown all the works connected with the wonderful bridge that he was then constructing across the Scheldt, and then sent him back to the besieged city with these words: ‘Go and tell those who sent you what you have seen. Tell them that I firmly intend either to bury myself beneath the ruin of this bridge or by means of it to pass into your city.’
There is a clear middle course between both extremes. Instead of being hung or shot or sent away scot free, a spy might fairly be made a prisoner of war. Suggestions in this sense were made at the Brussels Conference on the Laws of War. The Spanish delegate proposed that the custom of hanging or shooting detected spies should be abolished, and the custom be substituted of interning them as prisoners of war during the continuance of hostilities. The Belgian delegate proposed that in no case should they be put to death without trial; and it was even sought to establish a distinction between the deserts of the really patriotic and the merely mercenary spy. The feeling in fact made itself clearly visible, that an act of which a general might fairly avail himself could not in common justice be regarded as criminal in the agent. Between a general and a spy the common-law rule of principal and agent plainly holds good: ‘He who acts through another acts through himself.’ In a case of espionage either both principal and agent are guilty of a criminal act, or neither is. If the spy as such violates the laws of war, so does the general who employs him; and either deserves the same punishment. Were it not so, a general who should hire a bravo to assassinate an enemy would incur no moral blame, nor could be held to act outside the boundary of lawful and honourable hostilities.
In some other respects the Brussels Conference displayed the vagueness of sentiment that prevails about the use of spies in war. It was agreed between all the Powers that no one should be considered as a spy but one who secretly or under false pretences sought to obtain information for the enemy in occupied districts; that military men collecting such information within the zone of hostile operations should not be regarded as spies if it were possible to recognise their military character; and that military men, and even civilians, if their proceedings were open, charged with despatches, should not, if captured, be treated as spies; nor individuals who carried despatches or kept up communications between different parts of an army through the air in balloons. The German delegate proposed, with regard to balloons, that those who sailed in them might be first of all summoned to descend, then fired at if they refused, and if captured be treated as prisoners, not as spies. The rejection of his proposal implies that by the laws of modern war a balloonist is liable to be shot as a spy; so that, from the point of view of personal danger, the service of a balloon becomes doubly heroic. The Brussels Conference settled nothing, owing to the withdrawal of England from that attempt to settle by agreement between the nations the laws that should govern their relations in war-time; but from what was on that occasion agreed to or rejected may be gathered the prevalent practice of European warfare. Is it not then a little remarkable that for the dangerous service of espionage a different justice should be meted out to civilians and to military men; and that a patriot who risks his life in a balloon should also risk it in the same way as a spy, a deserter, or a traitor?
But whatever be the fate of a spy, and in spite of distinguished precedents to the contrary, men of honour will always instinctively shrink from a service which involves falsehood from beginning to end. The sentiment is doubtless praiseworthy: but what is the moral difference between entering a town as a spy and the military service of winning it by surprise? What, for instance, shall we think of the Spanish officers and soldiers who, dressed as peasants and with baskets of nuts and apples on their arms, gained possession of Amiens in 1597 by spilling the contents of their baskets and then slaying the sentinels as they scrambled to pick them up?[197] What of the officers who, in the disguise of peasants and women, and concealing daggers and pistols, got possession of Ulm for the Elector of Bavaria? What of the French who, in Dutch costume, and by supplications in Dutch to be granted a refuge from a pursuing enemy, surprised a fort in Holland in 1672?[198] What of Prince Eugene, who took the fortress of Breysach by sending in a large force concealed in hay-carts under the conduct of two hundred officers disguised as peasants?[199] What of the Chevalier Bayard, that favourite of legendary chivalry, who, having learnt from a spy the whereabouts of a detachment of Venetian infantry, went by night to the village where they slept, and with his men slew all but three out of some three hundred men as they ran out of their houses?[200] What of Callicratidas the Cyrenæan, who begged the commander of a fort to receive four sick soldiers, and sent them in on their beds with an escort of sixteen soldiers, so that they easily overpowered the guards and won the place for their general?[201] What of Phalaris, who, having petitioned for the hand of a commandant’s daughter, overcame the garrison by sending in soldiers dressed as women servants, and purporting to bear presents to his betrothed?[202] What of Feuquières, who, whilst pretending to lead a German force and praying for shelter from a snowstorm, affixed his pétards to the gates of Neuborg, and, having taken the town, put the whole of the garrison of 650 men to the sword?[203]
In what respect do such actions which are the everyday stratagems of a campaign, and count as perfectly fair, differ from the false pretences which constitute the iniquity of the spy? In this respect only—that whilst he bears his danger alone, in the case of a surprise the danger is distributed among numbers.
And, in point of fact, there was a time when the service of a surprise and that of espionage were so far regarded as the same that by the laws of war death was not only the allotted portion of the captured spy but of all who were caught in an endeavour to take a place by surprise. The rule, according to Vattel, was not changed, nor the soldiers who were captured in a surprise regarded or treated as prisoners of war, till the year 1597, when, Prince Maurice having failed in an attempt to take Venloo by surprise, and having lost some of his men, who were put to death for that offence, the new rule that has since prevailed was agreed upon by both sides for the sake of their future mutual immunity from that peril.
The usual rule laid down to distinguish a bad from a good stratagem is that in the latter there is no violation of an expressly or tacitly pledged faith. The violation of a conference, a truce, or a treaty has always therefore been reprobated, however commonly practised. But certain occurrences of history suggest the feasibility of corresponding stratagems which cannot be judged by so simple a formula and which therefore are of still uncertain right.
The first stratagem of this kind that suggests itself is that of forgery. Hannibal, having defeated and slain the Roman general Marcellus, and thereby become possessed of his seal, the Romans found it necessary to despatch messages to all their garrison towns that no more attention should be paid to orders purporting to come from Marcellus. The precedent suggests the use of forged despatches as a weapon of war. To obtain in time of peace, for use in time of war, the signatures of men likely to be hostile commanders, would obviously be of immense military service for purposes either of defence or aggression. The stratagem would be dishonourable in the highest degree; but, unfortunately, the standard of measurement in such cases is rather their effectiveness than their abstract morality.
The second stratagem of the sort is the stratagem of false intelligence. To what extent is it lawful to deceive an enemy by downright falsehood? The Chevalier Bayard, ‘without fear or reproach,’ when besieged by the Imperialists in Mézières, contrived to make the enemy raise the siege by sending a messenger with letters containing false information destined to fall into the hands of the enemy. The invention of the telegraph has increased the means of deceiving the enemy by false intelligence, and was freely so used in the Civil War of the United States. It is said to be better to secure the services of a few telegraph operators in a hostile country than to have dozens of ordinary spies; and for this reason, according to the eminent author of the ‘Soldier’s Pocket-Book’: ‘Before or during an action an enemy may be deceived to any extent by means of such men; messages can be sent ordering him to concentrate upon wrong points, or, by giving him false information, you may induce him to move as you wish.’