What is a dfghd?

Why did Grant decide to attack Jackson before attacking Vicksburg?

General Pemberton had his army defending Vicksbug. General Johnston had more troops oustide of Vicksburg and these threatened the Union with attack from the rear. Gen Grant may have thought he could take Vicksburg defenses by attacking from the river or from Port Hudson side. But he realized he had to lay a siege against Vicksburg. To do this, he had to defeat the forces that were outside of the city and surround the city. The Battle of Jackson(May 14) was fought to cut off re-inforcements from giving aid to the Confederates at Vicksburg. Then final battle occurred at Battle of Champion's Hill(May 16). This forced the Confederates back into the Vicksburg defenses. Link to a Map of Union advance: http://en.wikipedia.org/wiki/File:VicksburgCampaignAprilJuly63.png