Please answer the following question: Information: - A siege is a military blockade of a city or fortress with the intent of conquering by attrition or assault. This derives from "sedere", Latin for "to sit". Siege warfare is a form of constant, low-intensity conflict characterized by one party holding a strong, static defensive position. Consequently, an opportunity for negotiation between combatants is not uncommon, as proximity and fluctuating advantage can encourage diplomacy. - The Richmond and Petersburg Railroad moved passengers and goods between Richmond and Petersburg from 1838 to 1898. It survived the American Civil War and eventually merged into the main line on the east coast of the United States. History. The Richmond and Petersburg was founded in 1836 and sold in 1898. It survived a war and several financial panics. It went from a railroad that only connected trains from Richmond to Petersburg, to a part of an entire east coast system. It went from a slave economy to having fully paid employees. - Secession (derived from the Latin term "secessio") is the withdrawal of a group from a larger entity, especially a political entity (a country), but also any organization, union or military alliance. Threats of secession can also be a strategy for achieving more limited goals. - The Confederate States, officially the Confederate States of America (CSA or C.S.), commonly referred to as the Confederacy, was an unrecognized breakaway country of 11 secessionist slave states existing from 1861 to 1865. It was originally formed by seven slave states South Carolina, Mississippi, Florida, Alabama, Georgia, Louisiana, and Texas in the Lower South region of the United States whose regional economy was mostly dependent upon agriculture, particularly cotton, and a plantation system that relied upon the labor of African-American slaves. - The American Civil War was a civil war in the United States fought from 1861 to 1865. The Union faced secessionists in eleven Southern states grouped together as the Confederate States of America. The Union won the war, which remains the bloodiest in U.S. history. - The Department of Virginia and North Carolina was a United States Military department encompassing Union-occupied territory in the Confederate States during the Civil War. In 1863 it was formed by the merging of two previously existing departments: the Department of Virginia and the Department of North Carolina. In 1865 the two departments were once again separated. - Robert Edward Lee (January 19, 1807 October 12, 1870) was an American general known for commanding the Confederate Army of Northern Virginia in the American Civil War from 1862 until his surrender in 1865. The son of Revolutionary War officer Henry "Light Horse Harry" Lee III, Lee was a top graduate of the United States Military Academy and an exceptional officer and military engineer in the United States Army for 32 years. During this time, he served throughout the United States, distinguished himself during the MexicanAmerican War, and served as Superintendent of the United States Military Academy. - Ulysses S. Grant (born Hiram Ulysses Grant; April 27, 1822 July 23, 1885) was the 18th President of the United States (186977). Previously, as Commanding General of the United States Army (186469), Grant had worked closely with President Abraham Lincoln to lead the Union Army to victory over the Confederacy, in the American Civil War. As president, Grant implemented Congressional Reconstruction, often at odds with Lincoln's successor, Andrew Johnson. Twice elected president, Grant led the Republicans in their effort to remove the vestiges of Confederate nationalism and slavery, protect African-American citizenship, and supported unbridled industrial expansionism during the Gilded Age. - The Union Army was the land force that fought for the Union during the American Civil War, 1861 to 1865. It included the permanent regular army of the United States, which was augmented by massive numbers of temporary units consisting of volunteers as well as conscripts. The Union Army fought and eventually defeated the Confederate Army during the war. At least two and a half million men served in the Union Army; almost all were volunteers. About 360,000 Union soldiers died from all causes; 280,000 were wounded and 200,000 deserted. - The RichmondPetersburg Campaign was a series of battles around Petersburg, Virginia, fought from June 9, 1864, to March 25, 1865, during the American Civil War. Although it is more popularly known as the Siege of Petersburg, it was not a classic military siege, in which a city is usually surrounded and all supply lines are cut off, nor was it strictly limited to actions against Petersburg. The campaign consisted of nine months of trench warfare in which Union forces commanded by Lt. Gen. Ulysses S. Grant assaulted Petersburg unsuccessfully and then constructed trench lines that eventually extended over from the eastern outskirts of Richmond, Virginia, to around the eastern and southern outskirts of Petersburg. Petersburg was crucial to the supply of Confederate Gen. Robert E. Lee's army and the Confederate capital of Richmond. Numerous raids were conducted and battles fought in attempts to cut off the Richmond and Petersburg Railroad. Many of these battles caused the lengthening of the trench lines, overloading dwindling Confederate resources. - Charles A. Heckman was a brigadier general in the Union Army during the American Civil War . He fought in many of the early battles in North Carolina and later served in the Army of the James during the siege of Petersburg . - The Army of the James was a Union Army that was composed of units from the Department of Virginia and North Carolina and served along the James River during the final operations of the American Civil War in Virginia. Given the information above, choose from the list below the object entity that exhibits the relation 'occupation' with the subject 'charles adam heckman'. Choices: - army - general - military - officer - president - revolutionary - slave - united states army
A:
officer