The Threatened Outbreak in Maryland-Political Arrest and the Causes Therefor.

[For contemporaneous records covering military events in Maryland, including the Baltimore riots, the occupation of that city by the Union troops under General Butler, and the re-opening of communications between Washington and the North, see Series I, Vol. II.]

WASHINGTON, April 18, 1861.

His Excellency THOMAS H. HICKS,

Governor of Maryland.

SIR: The President is informed that threats are made and measures taken by unlawful combinations of misguided citizens of Maryland to prevent by force the transit of U. S. troops across Maryland on their way pursuant to orders to the defense of this capital. The information is from such sources and in such shape that the President thinks it his duty to make it known to you so that all loyal and patriotic citizens of your State may be warned in time and that you may be prepared to take immediate and effective measures against it.

Such an attempt could have only the most deplorable consequences; and it would be as agreeable to the President as it would be to yourself that it would be prevented or overcome by the loyal authorities and citizens of Maryland rather than averted by any other means.

I am, very respectfully, yours, &c.,

SIMON CAMERON,

Secretary of War.

BALTIMORE, April 19, 1861.

[The PRESIDENT.]

SIR: This will be presented to you by the Honorable H. Lennox Bond, George W. Dobbin and John C. Brune, esqs., who will proceed to Washington by an express train at my request in order to explain fully the fearful condition of affairs in this city. The people are exasperated to the highest degree by the passage of troops and the citizens are universally decided in the opinion that no more should be ordered to come.

The authorities of the city did their best to-day to protect both strangers and citizens and to prevent any collision but in vain; and but for their great efforts a fearful slaughter would have occurred.

Under these circumstances it is my solemn duty to inform you that it is not possible for more soldiers to pass through Baltimore unless they fight their way at every step.

I therefore hope and trust and most earnestly request that no more troops be permitted or ordered by the Government to pass through the city. If they should attempt it the responsibility for the blood shed will not rest upom me.

With great respect, your obedient servant,

GEO. WM. BROWN,

Mayor.