Soon after the landing at Bayou Sara, a party of cavalry rode in, bringing the news of Augur's battle of the 21st. Hearing that Augur was at that moment engaged with the enemy, Banks pressed forward his troops. In a violent storm of wind and rain Grover pushed on until he met Augur's outlying detachments. Then, finding all quiet, he went into bivouac near Thompson's Creek, north-west of Port Hudson. Paine followed, and rested on the Perkins plantation, a mile in the rear of Grover. Banks made his headquarters with Grover. Augur covered the front of the position taken up by the enemy after the battle of Plains Store. On the same day, the 22d, Sherman came up the river, landed at Springfield, and went into position on the Bayou Sara road on Augur's left. Thus at night on the 22d the garrison of Port Hudson was practically hemmed in.
On the 18th, Banks had ordered Augur to march with his whole disposable force to the rear of Port Hudson to prevent the escape of the garrison. As early as the 13th of May, while yet the plan of campaign was in suspense, Augur had sent Grierson with the cavalry and Dudley with his brigade to Merritt's plantation, near the junction of the Springfield Landing and Bayou Sara roads, to threaten the enemy and discover his movements. Dudley then took post near White's Bayou, a branch of the Comite, and remained in observation, covering the road to Clinton and the fork that leads to Jackson. On the 20th of May Augur moved the remainder of his force up to Dudley, in order to be ready to cover T. W. Sherman's landing at Springfield, as well as to meet the advance of the main column under Banks from Bayou Sara, now likely to occur at any moment. With Augur now were Dudley, Chapin, Grierson, Godfrey's squadron composed of troops C and E of the Louisiana cavalry, two sections of Rawles's battery, Holcomb's battery, and one section of Mack's commanded by Sergeant A. W. McCollin. At six o'clock on the morning of the 21st of May Augur marched toward the crossing of the Plains Store and Bayou Sara roads to seize the enemy's line of retreat and to open the way for Banks. When Grierson came to the edge of the wood that forms the southern boundary of the plain, his advance fell in with a detachment of the garrison under Colonel S. P. Powers of the 14th Arkansas regiment, and a brisk skirmish followed. The same afternoon Gardner sent out Miles, with his battalion, about 400 strong, and Boone's battery, to feel Augur's advance and perhaps to drive it away. This brought on the action known as the battle of Plains Store. Unfortunately, no complete reports of the affair were made and the regimental narratives are meagre.