Dennis Hart Mahan (April 2, 1802 - September 16, 1871) was a noted American military theorist and professor at the United States Military Academy at West Point. He was the father of American naval theorist Rear Admiral Alfred Thayer Mahan. April 2 is the 92nd day of the year (93rd in leap years) in the Gregorian calendar, with 273 days remaining. ... 1802 was a common year starting on Friday (see link for calendar). ... September 16 is the 259th day of the year (260th in leap years). ... 1871 was a common year starting on Sunday (see link for calendar). ... The Chapel at West Point The United States Military Academy, also known as West Point and USMA, is a U.S. military academy and former Army fort. ... Rear Admiral Alfred Thayer Mahan (27 September 1840 - 1 December 1914) was a United States Navy officer, naval strategist, and educator, widely considered the foremost theorist of sea power. ...

A native of New York City, Mahan graduated from West Point in 1824. He started teaching at the academy soon after and was sent to Europe to study. In 1830 he was promoted to professor of civil and military engineering. As a teacher of military science, Mahan promoted defensive tactics on the battlefield. It was from him that most of the cadets who became Civil War commanders, whether Union or Confederate, learned about entrenchment and fortifications, and how to conduct siege warfare. Nowhere was his influence greater in the Civil War than at the Siege of Petersburg, where his theories affected the lives of the nearly 200,000 men in the trenches around Petersburg and Richmond. Midtown Manhattan, looking north from the Empire State Building, 2005 New York City (officially named the City of New York) is the most populous city in the state of New York and the entire United States. ... Alternate meanings: West Point (disambiguation). ... 1824 was a leap year starting on Thursday (see link for calendar). ... World map showing location of Europe A satellite composite image of Europe Europe is geologically and geographically a peninsula, forming the westernmost part of Eurasia. ... 1830 was a common year starting on Friday (see link for calendar). ... The American Civil War was fought in the United States from 1861 until 1865 between the United States – forces coming mostly from the 23 northern states of the Union – and the newly-formed Confederate States of America, which consisted of 11 southern states that had declared their secession. ... The Union Army refers to the United States Army during the American Civil War. ... This article is in need of attention. ... Troops in the Siege of Petersburg faced the usual siege armaments — projectiles of all shapes and sizes and attacks on fortifications — but the Union added underground explosives to the mix. ... Trench warfare is a form of war in which both opposing armies have static lines of fortifications dug into the ground, facing each other. ... Petersburg is an independent city located in Virginia. ... Richmond is the capital of Virginia, a state (officially the Commonwealth of Virginia) of the United States of America. ...