premise: The Sierra Leone Civil War (1991–2002) began on 23 March 1991 when the Revolutionary United Front (RUF), with support from the special forces of Charles Taylor’s National Patriotic Front of Liberia (NPFL), intervened in Sierra Leone in an attempt to overthrow the Joseph Momoh government. The resulting civil war lasted 11 years, enveloped the country, and left over 50,000 dead.
hypothesis: The Sierra Leone Civil War ended in March 2002.
reason: Just because the civil war started in March 1991 and lasted 11 years does not mean the ending date of the civil war was for sure in the exact calendar month of March that it started in, but it could have.  Therefore the statement is neither definitely correct nor definitely incorrect.