Jersey is a heavily fortified island with coastal fortifications that date from different periods such as the English Civil War, the Napoleonic Wars, and Nazi Germany's occupation of the Channel Islands. The fortifications include castles, forts, towers, Martello towers, artillery batteries, and seawalls. Not infrequently, fortifications from one period are built on the site of earlier fortifications, or very near them, geography having remained the same even when firepower increased.