What was the greatest obstacle that the Union army faced at Vicksburg, and how did they overcome it?

I read so much on this ...were hills, surrounded by flooded marshlands & waters..army couldn't get through by foot..can't find a full explanation of this & how did they overcome it...no where to be found..I have to write a small paragraph on this...impossible !

You can organize information like this in a geographical pattern to make better sense. What did the Union army face first? What next? What next? and so on...

Here are some websites that may help:
http://www.historynet.com/americas-civil-war-digging-to-victory-at-vicksburg.htm

and a few here: http://www.google.com/#hl=en&sugexp=ldymls&xhr=t&q=union+army+problems+vicksburg&cp=29&qe=dW5pb24gYXJteSBwcm9ibGVtcyB2aWNrc2J1cmc&qesig=QtdAapJ3DVvftucKd29dvg&pkc=AFgZ2tllGbZmE9uDw9O4AnqWYV3HuShgdibramCrKchwq1nKkudUDwjS3_KcSt9UWLZpFLP0T3EEjqXVF5VXf4uOp6eCSy-Z2Q&pf=p&sclient=psy&source=hp&aq=f&aqi=&aql=&oq=union+army+problems+vicksburg&pbx=1&bav=on.2,or.r_gc.r_pw.&fp=951dc7972bfd90fb&biw=1169&bih=582

The greatest obstacle that the Union army faced at Vicksburg was the challenging terrain, specifically the hills and the flooded marshlands that surrounded the city. This made it extremely difficult for the Union troops to advance on foot or by traditional means. However, General Ulysses S. Grant devised a bold and innovative strategy to overcome this obstacle. He decided to launch a campaign to bypass and isolate the city by utilizing the waterways.

To achieve this, Grant ordered his troops to dig a canal that would divert the Mississippi River and allow Union boats to bypass the Confederate defenses. This effort, known as the Yazoo Pass Expedition, proved to be unsuccessful due to flooding and Confederate obstruction.

Undeterred, Grant then focused his attention on a different plan. He decided to move his army down the west bank of the Mississippi River, with the aim of crossing the river south of Vicksburg. This involved maneuvering his troops through extremely challenging, swampy terrain and finding suitable crossing points. Additionally, Grant had to overcome Confederate resistance and control a vast supply line that stretched along the river.

Despite the difficulties, Grant's determination and strategic thinking paid off. He ultimately succeeded in crossing the Mississippi River at Bruinsburg, south of Vicksburg, on April 30, 1863. This bold move allowed the Union army to establish a foothold on the eastern side of the river, where they launched a successful campaign that eventually led to the fall of Vicksburg on July 4, 1863.

In summary, the Union army overcame the greatest obstacle at Vicksburg—the challenging terrain—by employing innovative strategies such as attempting to dig a canal, and ultimately by finding a suitable crossing point south of the city. Grant's persistence and flexibility in adapting his tactics to the circumstances played a crucial role in the Union victory.