In 1859 he was a surgeon at Chimborazo Hospital in Virginia, serving soldiers from Florida during Civil War. In 1869 he moved to Tampa. In 1871, he contracted yellow fever aboard the steamer H. M. Cool from Cedar Key while treating a cabin boy.
He devoted his medical career to studying yellow fever and communicable diseases.
He also became more of an alcoholic. After agreeing to give up alcohol he was allowed to marry Matilda McKay, daughter of Captain James McKay.
Doctor Wall lived on the site of the Tampa Federal Savings and Loan Bank building. As mayor from 1878 to 1880, he worked to increase maritime trade.
He founded the Tampa Board of Trade and the Tampa Chamber of Commerce, serving as its first president
He helped lead construction of the railroad from northeastern Florida to Tampa, the settlement of Vincente Martinez Ybor and a large colony of Cuban and Spanish cigar makers in what is now part of Ybor City, and helped establish the phosphate industry. He was a delegate at the Florida Constitutional Convention of 1885. Wall is buried at the Oaklawn Cemetery in downtown Tampa.