The Government of the United States has been apprised that the Imperial German Government considered themselves to be obliged by the extraordinary circumstances of the present war and the measure adopted by their adversaries in seeking to cut Germany off from all commerce, to adopt methods of retaliation which go much beyond the ordinary methods of warfare at sea, in the proclamation of a war zone from which they have warned neutral ships to keep away. This government has already taken occasion to inform the Imperial German Government that it cannot admit the adoption of such measures or such a warning of danger to operate as in any degree an abbreviation of the rights of American shipmasters or of American citizens bound on lawful errands as passengers on merchant ships of belligerent nationality, and that it must hold the Imperial German Government to a strict accountability for any infringement of those rights, intentional or incidental. It does not understand the Imperial German Government to question these rights. It assumes, on the contrary, that the Imperial Government accept, as of course, the rule that the lives of non-combatants, whether they be of neutral citizenship or citizens of one of the nations at war, cannot lawfully or rightfully be put in jeopardy by the capture or destruction of an unarmed merchantman, and recognize also, as all other nations do, the obligation to take the usual precaution of visit and search to ascertain whether a suspected merchantman is in fact of belligerent nationality or is in fact carrying contraband of war under a neutral flag. The Government of the United States, therefore, desires to call the attention of the Imperial German Government with the utmost earnestness to the fact that the objection to their present method of attack against the trade of their enemies lies in the practical impossibility of employing submarines in the destruction of commerce without disregarding those rules of fairness, reason, justice, and humanity which all modern opinion regards as imperative. It is practically impossible for the officers of a submarine to visit a merchantman at sea and examine her papers and cargo. It is practically impossible for them to make a prize of her; and, if they cannot put a prize crew on board of her, they cannot sink her without leaving her crew and all on board of her to the mercy of the sea in her small boats. These facts, it is understood, the Imperial German Government frankly admit. We are informed that in the instances of which we have spoken time enough for even that poor measure of safety was not given, and in at least two of the cases cited not so much as a warning was received. Manifestly, submarines cannot be used against merchantmen, as the last few weeks have shown, without an inevitable violation of many sacred principles of justice and humanity.