And it is even true, that from this battle General Walker’s prospects clouded rapidly.  A proclamation, issued by the Costa-Rican government, promising fugitive filibusters free passage to the United States, found its way into Rivas, and immediately worked immense mischief, and was, indeed, the instrument of his overthrow.  The men had no sooner seen it than they began to leave as fast as they found opportunities to escape.  Guards were placed around the town, and spies in every company; but it was of no avail; and every morning it was rumored through the camp that this or that number had got off for Costa Rica during the night.  General Walker, in a speech which he made a few days after to infuse new spirit, said that these were the cowards,—­whose absence was beneficial, and from whom it was well that the army should be purged.  However, this was exaggerated.  It is true, doubtless, that there were many leaving merely from fear, who would have chosen to stay with him, rather than trust to the promises of a people believed to be treacherous and promise-breaking, and whose hatred they had incurred,—­had the battles of San Jorge and Obraja been successful.  And, indeed, the filibuster ranks were not wanting in cowards.  Cowards might be induced to come on a desperate enterprise like this, through misrepresentation by Walker’s own agents; through mere thoughtlessness, or mistake,—­not knowing what soldier’s metal was in them; or, with the bayonet of Hunger against their backs at home, they might be unmindful of any other bayonet on the distant shore of Nicaragua. (It should be musket-shot, however; for the greasers never found heart to use the bayonet.) And then again, many, who, when they first reached Nicaragua, were no cowards, after a few months’ stay, became changed,—­by the depressing effects of fever, by loss of confidence in their drunken officers, and by the absence of all incentive to fight stoutly for a leader so unpopular as Walker.  It was a common saying, that in this army an old rule was reversed,—­the veterans were worse fighters than the recruits.  The soldier was at his best when he first landed upon the Isthmus, raw and healthy.  After that, he rapidly deteriorated, losing spirit with every battle, until he became at last a thoroughbred coward.  Seven or eight greasers to one filibuster was said to be good fighting, at one time; but now three or four to one was thought to be great odds; and before the game ended, I hear, they were become equally matched, man for man, almost.  But, whatever General Walker said in his speech, this class of weak ones were not always the deserters.  It required some little energy or strength of legs, with which these were unfurnished, to go over to the enemy at San Jorge, or walk down to Costa Rica; and the fact was, that from the first many of the healthiest and liveliest men, whose defection could least be borne, were leaving,—­not from fear, mainly, but because by this proclamation they were offered the first opportunity to escape from a disagreeable service to which they thought themselves bound by no tie of love or honor.