Boy-Ed, at that, did not seem to be so deeply involved as Papen was. He protested that he had no part in conspiring with Huerta, and had never seen the Mexican "ex-President." But it was known that Rintelen had had dealings with Huerta, and that Rintelen had received from Boy-Ed at least half a million dollars. The dealings of Captain von Papen with Huerta were too thoroughly disclosed to admit of denial. Germany, beginning years before, had built up in this country an extensive spy system, which kept it informed not only of military developments, but of what was done in every branch of industry. When the European war began they used every possible means of preventing the manufacture of munitions or supplies for the Allies. Nearly every large factory or plant had in its employ workmen who were paid agents of the German Government. That they could secure information of what was going on was not so menacing as what they might do, for one or two men could damage machinery so as to retard work for months. There were explosions in munition plants, machinery was at times mysteriously wrecked, shells were damaged; and while the cause seldom could be definitely determined, it was the general belief that many of these "accidents" were the work of German agents. The Office of Naval Intelligence, whose function in peace times is to gather naval information from all parts of the world, had a more difficult task to perform when war came. An Investigation Section was formed to seek out and take into custody persons who were, by sabotage, explosion, fomenting strikes or other means, seeking to prevent or retard the manufacture of munitions; to discover and thwart any attempt to damage vessels, shipyards, bases or factories; to counteract German propaganda and, in general, restrain the activities of Germans and German sympathizers. In each naval district there was an Aide for Information, reporting to Rear Admiral Roger Welles, Director of Naval Intelligence, at Washington. Each district was further sub-divided into sections with representatives working under the district aid. The activity of these aides was tremendous, especially in our large ports of entry, New York, Boston, Philadelphia, Baltimore, and Norfolk. Arrests of suspects sent fear into the hearts of any who might be plotting sabotage. In one day I ordered the arrest of more than a score in one plant. Ships from countries near Germany were examined from truck to keel for contraband, or papers or literature that might convey secret messages. Passengers and crews were carefully scrutinized. Close inspection and censorship of mails and cables prevented Germany from communicating with its agents in this country, and also prevented them from sending out military information.