Question: What position was held by the individual who defeated the last song emperor of the nation that is the biggest owner of us debt?

<P0-S0> The Song dynasty is divided into two distinct periods, Northern and Southern. <P0-S1> During the Northern Song (Chinese: 北宋; 960 -- 1127), the Song capital was in the northern city of Bianjing (now Kaifeng) and the dynasty controlled most of what is now Eastern China. <P0-S2> The Southern Song (Chinese: 南宋; 1127 -- 1279) refers to the period after the Song lost control of its northern half to the Jurchen Jin dynasty in the Jin -- Song Wars. <P0-S3> During this time, the Song court retreated south of the Yangtze and established its capital at Lin'an (now Hangzhou). <P0-S4> Although the Song dynasty had lost control of the traditional ``birthplace of Chinese civilization ''along the Yellow River, the Song economy was still strong, as the Southern Song Empire contained a large population and productive agricultural land. <P0-S5> The Southern Song dynasty considerably bolstered its naval strength to defend its waters and land borders and to conduct maritime missions abroad. <P0-S6> To repel the Jin, and later the Mongols, the Song developed revolutionary new military technology augmented by the use of gunpowder. <P0-S7> In 1234, the Jin dynasty was conquered by the Mongols, who took control of northern China, maintaining uneasy relations with the Southern Song. <P0-S8> Möngke Khan, the fourth Great Khan of the Mongol Empire, died in 1259 while besieging the city of Chongqing. <P0-S9> His younger brother Kublai Khan was proclaimed the new Great Khan, though his claim was only partially recognized by the Mongols in the west. <P0-S10> In 1271, Kublai Khan was proclaimed the Emperor of China. <P0-S11> After two decades of sporadic warfare, Kublai Khan's armies conquered the Song dynasty in 1279. <P0-S12> The Mongol invasion led to a reunification under the Yuan dynasty (1271 -- 1368). <SEP> <P1-S0> Kublai (; ; ) was the fifth Khagan (Great Khan) of the Mongol Empire ("Ikh Mongol Uls"), reigning from 1260 to 1294 (although due to the division of the empire this was a nominal position). <P1-S1> He also founded the Yuan dynasty in China as a conquest dynasty in 1271, and ruled as the first Yuan emperor until his death in 1294. <SEP> <P2-S0> As of July 31, 2018, debt held by the public was $15.6 trillion and intragovernmental holdings were $5.7 trillion, for a total or ``National Debt ''of $21.3 trillion. <P2-S1> Debt held by the public was approximately 77% of GDP in 2017, ranked 43rd highest out of 207 countries. <P2-S2> The Congressional Budget Office forecast in April 2018 that the ratio will rise to nearly 100% by 2028, perhaps higher if current policies are extended beyond their scheduled expiration date. <P2-S3> As of December 2017, $6.3 trillion or approximately 45% of the debt held by the public was owned by foreign investors, the largest being China (about $1.18 trillion) then Japan (about $1.06 trillion). <SEP> <P3-S0> following the defeat of the usurper known as constantine iii, jovinus was proclaimed emperor at mainz in 411, a puppet supported by gundahar, king of the burgundians, and goar, king of the alans. <P3-S1> jovinus kept his position in gaul for two years, long enough to issue coinage that showed him wearing the imperial diadem. <P3-S2> he was supported by a number of local gallo-roman nobles who had survived constantine's defeat. <SEP> <P4-S0> ``san francisco (be sure to wear flowers in your hair) ''is an american pop music song, written by john phillips of the mamas & the papas, and sung by scott mckenzie. <P4-S1> the song was produced and released in may 1967 by phillips and lou adler, who used it to promote their monterey international pop music festival held in june of that year. <P4-S2> john phillips played guitar on the recording and session musician gary l. coleman played orchestra bells and chimes. <P4-S3> the bass line of the song was supplied by session musician joe osborn. <P4-S4> hal blaine played drums. <P4-S5> the song became one of the best - selling singles of the 1960s in the world, reaching the fourth position on the us charts and the number one spot on the uk charts.