These attacks failed , but they continued to wear down the city 's defenders .
A coordinated series of attacks on the city were launched in early July 1864 , including an amphibious assault on Fort Johnson and an invasion of Johns Island .
These attacks failed , but attacks continued to wear down the city 's defenders .
A coordinated series of attacks on the city were launched in early July 1864 , including an amphibious assault on Fort Johnson and an invasion of Johns Island .