Information:  - The Roman Empire (Koine and Medieval Greek:   , tr. ) was the post-Roman Republic period of the ancient Roman civilization, characterized by government headed by emperors and large territorial holdings around the Mediterranean Sea in Europe, Africa and Asia. The city of Rome was the largest city in the world BC AD, with Constantinople (New Rome) becoming the largest around 500 AD, and the Empire's populace grew to an estimated 50 to 90 million inhabitants (roughly 20% of the world's population at the time). The 500-year-old republic which preceded it was severely destabilized in a series of civil wars and political conflict, during which Julius Caesar was appointed as perpetual dictator and then assassinated in 44 BC. Civil wars and executions continued, culminating in the victory of Octavian, Caesar's adopted son, over Mark Antony and Cleopatra at the Battle of Actium in 31 BC and the annexation of Egypt. Octavian's power was then unassailable and in 27 BC the Roman Senate formally granted him overarching power and the new title "Augustus", effectively marking the end of the Roman Republic.  - Gaius Julius Caesar (13 July 100 BC  15 March 44 BC), known as Julius Caesar, was a Roman politician, general, and notable author of Latin prose. He played a critical role in the events that led to the demise of the Roman Republic and the rise of the Roman Empire.  - Opera (English plural: "operas"; Italian plural: "opere" ) is an art form in which singers and musicians perform a dramatic work combining text (libretto) and musical score, usually in a theatrical setting. In traditional opera, singers do two types of singing: recitative, a speech-inflected style and arias, a more melodic style. Opera incorporates many of the elements of spoken theatre, such as acting, scenery, and costumes and sometimes includes dance. The performance is typically given in an opera house, accompanied by an orchestra or smaller musical ensemble, which since the early 19th century has been led by a conductor.  - The Dangerous Book for Boys, by Conn and Hal Iggulden, is a guidebook published by HarperCollins, aimed at boys "from eight to eighty." It covers around eighty topics, including how to build a treehouse, grow a crystal, or tell direction with a watch. Also included are famous quotes, stories, battles, and phrases that "every boy should know." It was published in the UK on 5 June 2006, and reached number one in the UK non-fiction charts several times, selling over half a million copies.  - The history of comics has followed different paths in different cultures. Scholars have posited a pre-history as far back as the Lascaux cave paintings. By the mid-20th century, comics flourished particularly in the United States, western Europe (especially in France and Belgium), and Japan. The history of European comics is often traced to Rodolphe Töpffer's cartoon strips of the 1830s, and became popular following the success in the 1930s of strips and books such as "The Adventures of Tintin". American comics emerged as a mass medium in the early 20th century with the advent of newspaper comic strips; magazine-style comic books followed in the 1930s, in which the superhero genre became prominent after Superman appeared in 1938. Histories of Japanese comics and cartooning ("") propose origins as early as the 12th century. Modern comic strips emerged in Japan in the early 20th century, and the output of comics magazines and books rapidly expanded in the post-World War II era with the popularity of cartoonists such as Osamu Tezuka. had a lowbrow reputation for much of its history, but towards the end of the 20th century began to find greater acceptance with the public and in academia.  - Historical fiction is a literary genre in which the plot takes place in a setting located in the past. Historical fiction can be an ambiguous term: frequently it is used as a synonym for describing the historical novel; however, the term can be applied to works in other narrative formats, such as those in the performing and visual arts like theatre, opera, cinema, television, comics, and graphic novels.  - The Gods of War is the fourth novel in the Emperor series , written by British author Conn Iggulden . The series is historical fiction following the life of Julius Caesar .  - Conn Iggulden (born ) is a British author who mainly writes historical fiction. He also co-authored "The Dangerous Book for Boys".    Given the information, choose the subject and object entities that have the relation of 'publisher'.
A:
the gods of war , harpercollins