No. 20.
Mr. Osborn to Mr. Evarts.

No. 287.]

Sir: A bloody battle took place yesterday a few miles southwest of the city, in which it appears the national forces were victorious, as the provincial forces fell back upon the city and caused a great panic among the inhabitants.

General Arias, after his battle with General Racedo, on the 17th instant, fell back within three miles of the city, when he was re-enforced by the provincial troops of the city.

On Sunday, the 20th instant, a body of national troops attacked the south part of the city and a very sharp engagement took place, in which some 20 on the part of the provincial troops were killed and wounded. This engagement was the result of mistaken orders.

General Levalle, with the force from the southern frontier, arrived. Supposing the city surrounded by the national forces, he advanced in this direction on the city. Having surprised the city forces, as well as finding himself surprised, he fell back and joined the national forces sent to meet him at Lanús. On Monday, with the additional force, he attacked General Arias, and, after fighting the whole day, drove him back into and surrounded the city.

The losses, as reported, on both sides amounted, in killed and wounded, to about 1,000. The general feeling is, even in the city, that the provincial forces have been worsted, and that the national forces have the advantage and are probably the masters of the situation and, in all probability, will soon force a peace, as the city cannot stand a siege for any great length of time.

I have, &c.,

THOS. O. OSBORN.