Roger...I would say yes to the pontoon bridge. However the bridge crossed the James at Wilcox Landing just a few miles east of Harrison's Landing and ended on the south bank at Flowerdew Hundred Plantation. The bridge was built in less than 24 hours and was 2500 feet long. It held the record for longest pontoon bridge ever constructed until World War Two. It took 3 days for all of Grant's 100,000+ army to cross. Deep Bottom was the peninsula or point of land between where the Appomattox and James Rivers come together and is further upriver. On the south bank of the James/Appomattox confluence was City Point and the present day town of Hopewell. Grant's troops pushed on to Petersburg after their crossing. Benjamin Butler's troops remained "in the bottle" at Deep Bottom or "Bermuda Hundred" venturing out to harrass the Confederates at Proctor's Creek, The Halfway House, and Chester Station. The accounts of your ancestor sound correct however I think he has his locations confused a little. Google search City Point, Bermuda Hundred, Seige of Petersburg, and Benjamin Butler. You should be able to locate some maps that will show you the landmarks that your ancestor mentions and their relation to each other. There is actually a dead Cypress Tree that is estimated to be over 350 years old that shows up in pictures of the pontoon bridge. The tree is still there and helped researchers in the late 1980s to determine the exact location of the bridge by overlaying present day and historic photos. I live in New Kent County, Virginia and Grant's army came right through here on their retreat from Cold Harbor. My house is 3/4 of a mile from The Richmond-York River Railroad at Summit Station. If there is anything I can do to help with your research let me know.

Keith