It's about as long as King Tut's reign.
(a.k.a. Tutankhamun, a.k.a. Tutankhaten, a.k.a. tVwa:t-ʕa:nəx-ʔaˡma:n) (1333 BCE - 1324 BCE)
It's about as long as FDR's Presidential Term.
(a.k.a. Franklin Roosevelt, a.k.a. Franklin Delano Roosevelt) (1933-45)
It's about one-and-two-fifths times as long as The Revolutionary War (American).
In other words, 315.9 fortnights is 1.445 times the length of The Revolutionary War (American), and the length of The Revolutionary War (American) is 0.692 times that amount.(a.k.a. American War of Independence) (1775-83)
It's about one-and-nine-tenths times as long as The Construction of the Chunnel.
In other words, 315.9 fortnights is 1.895 times the length of The Construction of the Chunnel, and the length of The Construction of the Chunnel is 0.5277 times that amount.(a.k.a. Channel Tunnel, a.k.a. Le tunnel sous la Manche) (1987 thru 1994) (Folkstone, Kent, UK to Coquelles, Pas-de-Calais, France)
It's about two times as long as World War II.
In other words, 315.9 fortnights is 2.016 times the length of World War II, and the length of World War II is 0.496 times that amount.(a.k.a. Second World War, a.k.a. WWII, a.k.a. WW2) (1939 - 1945)
It's about two-fifths as long as Pius IX's reign.
In other words, 315.9 fortnights is 0.3826 times the length of Pius IX's reign, and the length of Pius IX's reign is 2.614 times that amount.(a.k.a. Pope Blessed Pius IX, a.k.a. Giovanni Maria Mastai-Ferretti) (1792-1878)
The longest reigning Pope in the Church's history, Pius IX reigned from June 16th, 1846 to February 7th, 1878 — 825.6 fortnights. As the last monarchical Pope, he ruled over 3,000,000 subjects in the Papal States until 1870.
It's about three times as long as World War I.
In other words, 315.9 fortnights is 2.77 times the length of World War I, and the length of World War I is 0.361 times that amount.(a.k.a. First World War, a.k.a. Great War, a.k.a. World War, a.k.a. War to End All Wars, a.k.a. WWI, a.k.a. WW1) (1914 - 1918)
World War I is considered to have begun with the assassination of Austrian Archduke Franz Ferdinand on June 28th, 1914 and to have lasted until the signing of the armistice with Germany on November 11th, 1918, for a total of 114 fortnights. However, the Treaty of Versailles which ended conflicts between the major powers was not signed until June 28th, 1919 and the last formal peace treaties were not signed until August 23rd, 1923 — 125 fortnights after the armistice was signed.