Our Washington Correspondence. Mr. Pierce's European Diplomacy — The Official Despatches of Mr. Belmont Neutralized by Private Letters of the President — Mr. Pierce's Russian Diplomacy — His Foreign Policy — St. Domingo Treaty — Spanish and Cuban Affairs.

The Pierce diplomacy, as such recognized through Europe and the United States, is winning for its originators and supporters a reputation which will be well remembered long after his Presidential term has expired.

The representative of the United States to Belgium was a studied deception, official and personal, with all the members of his Cabinet. Jealousy and suspicion, between member and member, were in part the natural consequences of this system of deceit, and this state of feeling was on the increase, until an explanation was forced, and the cause of the difficulty was traced to the treachery of the President.

This discovery was followed up by rumors of Cabinet dissensions, threats of exposure of the President's duplicity, and a general loss of confidence throughout the newspaper press and the public mind. Failing at home in character, Mr. Soulé, the Minister of the United States to Spain, was honored as the first upon whom the experiment was to be tried. His failure at Madrid, is the by-word of all diplomatic circles throughout Europe. Nor was to the United States the attainment of the object which was to have been the special feature of the mission. The representative of the United States fell at once in Spanish estimation; it created difficulties between the United States Minister and the court to which he was accredited, until finally discovering that the President's confidential diplomacy had been the main cause of the trouble, running as it did in opposition to instructions received from the State Department, he expressed a preference to do his duty to the United States, willing, for the reputation of his country, to suffer the blame of 'Pierce diplomacy,' rather than offer his sovereign a reason that details would have compromised or disgraced the head of the American republic.

If the first essay of General Pierce's new system of 'Pierce diplomacy' was suggested in the ever-memorable Ostend conference, it was as unfortunate in its intended continuation. This convention originated and its proceedings were dictated by President Pierce. The belligerent character given to it was a proposition from the intrigant, who through private influence obtained the position of Chairman of Foreign Relations, imagining that their publicity would add support to his reputation as a skilful diplomat. How stands the case? Upon the arrival of French steamers of war, who entered the Dominican harbor, after the convention at Ostend, the French and Spanish agents, and the Spanish and French flags were raised, and the Dominican Minister for Foreign Affairs, in a letter to our representative, by the French Minister for Foreign Affairs:—'Whether His Majesty should regard Santo Domingo as a Spanish or a French colony, is not yet decided;' and his 'reasons for asking the question were: First, the proceedings at the Ostend Convention, official transcripts of which had been placed before the United States Congress, and copies of which had been forwarded to the French Government by the President.' A reading of the Ostend documents will show how far the question, thus submitted, was an improper one.

The same attempt at secrecy of General Pierce has been felt, as well as in England, by the same species of confidence which our ministers have hitherto enjoyed. It would be difficult to credit this towards his subordinates, but it is nevertheless known and understood to have been the case. Nor is it to be regarded the humiliating abandonment of our claim for damages committed by the government at the Hague? Mr. Marcy writes one dispatch, and General Pierce writes another, for an immediate settlement of the amount specified. He does so; and by this means the rights of American citizens and assistance to her claims are made. Daily interviews with the ministry are asked for and obtained, and the threats of General Pierce made to bear upon the question at a specified moment, and the glad news is despatched to Washington that the business is settled. The new thought strikes the President, and no blame whatever is chargeable to the Hague government, for it was only following out General Pierce's suggestion. An enviable position truly for an American representative to be placed in. To the other States of Europe, to which we will return, after a visit to St. Domingo. A treaty with this government was well known to have been a favorite idea with General Pierce. Through the ability of his agent, Gen. Cazneau, a most liberal one was agreed upon, and to make it valid, a little formal ceremony was necessary. This treaty brought a protest from the British and French Ministers at Washington, which had the recognition of Mr. Pierce. The British and French agents, who entered the Dominican harbor, and the British and French flags were raised, and the Dominican Minister for Foreign Affairs, in a letter to our representative, by order of his government, stated that the treaty between St. Domingo and the United States was ratified. This flagrant interference was submitted to by our President, who acknowledged the propriety of the protest of the foreign representatives against a treaty with that government, and in part forcing our Minister to abandon the treaty altogether. We shall return to this subject at some future day, and the following somewhat interesting facts have been furnished us:—'Does General Pierce imagine that he has established a secret diplomacy?' I thought a brief history of this statesman's operations in that department of politics, might not be without its interest.

The second edition of Mr. Pierce's system of secret diplomacy, while on terms of amity and friendship with another nation, has been carried out by him, while such nations as may be waging war to their injury and detriment, are compelled to suffer, by the standard of right and wrong, and under the cover of the foreign policy of General Pierce. Judge for yourself of its truth and justice. Shortly after the departure of our government of the present war in the East it was understood that Mr. Belmont, who had returned home a very few weeks, had declared his sympathy with Russia, and was determined to assist Russia, even with the whole cabinet. Marcy, in his despatches to Mr. Belmont, instructed him to remain strictly neutral, to observe all proper respect for the subject, and condemned everything bearing upon it, which was strictly carried out by our Minister during the present war. Further than this Marcy could not go. But Gen. Pierce, in his private correspondence with Mr. Belmont, urged upon him to aid Russia to the utmost of his power, copies of which were given to scientific and worthy American, then in Europe, who transmitted them to the French Government. The result was that the Emperor, as a result of the war, which was strongly in favor of Russia, demanded an explanation from Mr. Belmont.

This confidence led to private correspondence, until Mr. Marcy, who had been kept in ignorance of all that had passed, was compelled to send one dispatch after another, giving whatever is of interest to our Minister at the Hague. Knowing these facts, instructions were sent to the Minister for Foreign Affairs at the Royal Court, and a more disgraceful diplomatic transaction has never taken place. It is probable that this discovery led to the resignation of Mr. Soulé, who was also a resident. It will be remembered that a week or two before the resignation of Mr. Soulé, a rumors prevailed throughout the United States, and at Washington of important despatches from our Minister at Madrid. A messenger arrived, and went directly to the President's house, who received them from the Minister, but instead of giving them to Mr. Marcy, he put them in his pocket and took them with him to his country residence. Mr. Marcy called for them, but could not get them. Enough was known, however, as to their contents, which he had broadly hinted at, instead of performing his duty as a public officer, he, like a southern statesman, the proposed personal friend of General Pierce, preferred to use the President as a channel of private interviews between our Minister and the Prudential government, which resulted in Mr. Marcy tendering his resignation, which Gen. Pierce refused to accept, and indirectly intimating that Prussia would be regarded as a neutral States in the event of French or English interference.

In connection with this subject, we would add, that our representative at Russia, dictated by President Pierce, without the knowledge of the Secretary of State, sent a dispatch to St. Petersburg, and in the opening notes, it was found that Austria had spoken insultingly of our President, and Mr. Pierce, through his private secretary, sent a note to our Minister at Russia to presume that no such communication would have been made by Austria, without his authority, and that an explanation must be demanded of Austria. Such was the position of the United States and Russia; and it is still better understood, that should any future belligerent action take place in carrying out the act of Congress relative to the building of six war steamers, which the navy will require, if required, every available aid from three of the European Powers will be placed at the disposal of Russia. President Pierce, foreseeing this state of things, and with the view of securing his election, has taken these means to accomplish it, and when these facts are made when it is known to that, produce so important an effect, in forcing upon the United States a violation of treaty stipulation with foreign governments?

The subject will be brought up at the next session of Congress, when it will be vain for General Pierce to try to screen himself, and he will be held responsible for his actions foreign from the moment of his inauguration.