Numbers 96.] FORT SUMTER, S. C., April 8, 1861.

Colonel L. THOMAS, Adjutant-General, Washington, D. C.:

COLONEL: I have the honor to report that the South Carolinians have since about noon yesterday been very actively engaged in strengthening their works on Morris Island. I pray that God will avert the storm which seems impending over us, and restore amicable and permanently pacific relations between the States who still stick to the old Union and those who have formed another Government in the South.

I am, colonel, very respectfully, your obedient servant,

ROBERT ANDERSON,

Major, First Artillery, Commanding.

P. S. - I omitted acknowledging the receipt of the letter from the honorable Secretary of the 4th instant.

[Inclosure Numbers 3.]

Numbers 96.] FORT SUMTER, S. C., April 8, 1861.

Colonel L. THOMAS, Adjutant-General U. S. Army:

COLONEL: I have the honor to report that the resumption of work yesterday (Sunday) at various points on Morris Island, and the vigorous prosecution of it this morning, apparently strengthening nearly all the batteries which are under the fire of our guns, shows that they either have received some news from Washington which has put them on the qui vive or that they have received orders from Montgomery to commence operations here. I am preparing by the side of my barbette guns protection for our men from the shells, which will be almost continuously bursting over or in our work.

I had the honor to receive by yesterday's mail the letter of the honorable Secretary of War, dated April 4, and confess that what he there states surprises me very greatly, following as it does and contradicting so positively the assurance Mr. Crawford telegraphed he was authorized to make. I trust that this matter w ill be at once put in a correct light, as a movement made now, when the South has been erroneously informed that none such will be attempted, would produce most disastrous results throughout our country.

It is, of course, now too late for me to give any advice in reference to the proposed scheme of Captain Fox. I fear that its result cannot fail to be disastrous to all concerned. Even with his boat at our walls the loss of life (as I think I mentioned to Mr. Fox) in unloading her will more than pay for the good to be accomplished by the expedition, which keeps us, if I can maintain possession of this work, out of position, surrounded by strong works, which must be carried to make this fort of the least value to the United States Government.

We have not oil enough to keep a light in the lantern for one night. The boats will have, therefore, to rely at night entirely upon other marks. I ought to have been informed that this expedition was to come. Colonel Lamon's remark convinced me that the idea, merely hinted at to me by Captain Fox, would not be carried out. We shall strive to do our duty, though I frankly say that my heart is not in the was which I see is to be thus commenced. That God will still avert it, and cause us to resort to pacific measures to maintain our rights, is my ardent prayer.

I am, colonel, very respectfully, your obedient servant,

ROBERT ANDERSON,

Major, First Artillery, Commanding.