The Siege of St. Petersburg (The Leningrad Blockade) was one of the most brutal acts in WWII--Germans & Finns choked off the city for over 800 days--many starved and froze to death--survivors resorted to desperate measures for warmth and food. This seems to be a background event in WWII, but it was one of the most destructive, strategic, complicated, and lethal blockades in history and many people don't know about it. I learned of it reading City of Thieves by Davi Benioff.
Roman bicircumvallation. A circumvallation is a line of fortifications, built by the attackers around the besieged fortification facing towards the enemy fort. The resulting fortifications are known as 'lines of circumvallation'. They generally consist of earthen ramparts and entrenchments that encircle the besieged city. The line of circumvallation can be used as a base for launching assaults against the besieged city or for constructing further earthworks closer to the city.
April 8, 1968 / The siege of Khe Sanh ends with the withdrawal of NVA troops from the area as a result of intensive American bombing and the reopening of Route 9. NVA losses during the siege are estimated up to 15,000. U.S. Marines suffered 199 killed and 830 wounded. 1st Cavalry suffered 92 killed and 629 wounded reopening Route 9. The U.S. command then secretly shuts down the Khe Sanh air base and withdraws the Marines. ~ Vietnam War