General John Pegram was in progress. Pegram marched
from East Tennessee about the middle of March, reaching Danville,
Ky., on the 23d. He spread reports that he was the advance-guard of
a large force of all arms intending a serious invasion of the State.
These exaggerations had their effect, and the disturbance in the
Department of the Ohio was out of proportion to the strength of the
hostile column. [Footnote: Letter of Governor Robinson, Official
Records, vol. xxiii. pt. ii. p. 97; _Id_., pp. 121, 126.] The troops
belonging to the post at Danville retreated to the hither side of
the Kentucky River at Hickman's Bridge, where they took up a
defensive position. They saved the railway bridge from destruction,
and Brigadier-General Quincy A. Gillmore, who commanded the District
of Central Kentucky with headquarters at Lexington, was able to
concentrate there a sufficient force to resume the offensive against
Pegram.

Burnside ordered reinforcements to Gillmore from the other parts of
Kentucky, and Pegram, whose report indicates that a foray for beef,
cattle, and horses was the principal object of his expedition,
commenced his retreat. Gillmore followed him up vigorously,
recapturing a considerable part of the cattle he had collected, and
overtaking his principal column at Somerset, routed him and drove
him beyond the Cumberland River.

The month of March had begun with pleasant spring weather, and on
the 15th General Wright had written to Halleck that an invasion of
Kentucky was probable, especially as Rosecrans showed no signs of
resuming the aggressive against Bragg's army in middle Tennessee.
[Footnote: _Id_., p. 143.] In Halleck's letter of instructions to
Burnside as the latter was leaving Washington to relieve Wright, the
general plan of an advance on East Tennessee in connection with that
of Rosecrans toward Chattanooga was outlined, but the
General-in-Chief acknowledged that the supply of an army in East
Tennessee by means of the wagon roads was probably impracticable.
[Footnote: _Id_., p. 163.] He pointed out the necessity of reducing
the number and size of garrisons in the rear, and making everything
bend to the great object of organizing the army for active
initiative against the enemy. He recommended building block-houses
to protect the principal bridges on the railroads, where very small
garrisons could give comparative security to our lines of
communication. This plan was ultimately carried out on a large