The sea going galley was primarily powered by oars which can bee seen in the water mid-ship. Sails were available and used in favorable winds.
The Algerian victory over the invading Spanish in the 1775 Battle of El Harrach is commemorated in this banknote.
Also known as the Algiers Expedition of 1775, The Spanish Empire had expended considerable resources preparing for the seizure of Algiers. The intent was to teach to Ottoman rulers that the Spanish Empire would not be intimidated and would not back down. The Spaniards had the year before successfully resisted a British backed Ottoman siege in Morocco.
The Spanish expedition was huge. 300 ships, consisting of about 70 warships and 230 transport ships, carried 22,000 men and considerable war material to the shores of Algiers. But the Algerians were ready. Having been informed by spies of the impending campaign, the developed their plan.
The Spaniards poorly selected a landing ground full of dunes. Shortly after disembarkation they found their cannon mired in the sand. Light Algerian resistance soon fled the scene however, and the Spaniards completed their disembarking. The Algerian flight was a ruse, Once the Spanish army was free of their ships, an experienced Algerian army charged toe Spaniard, including a camel charge of experienced desert warrior tribesman and the Spaniards were completely overwhelmed. They fled to their ships leaving behind 3,000 dead and many weapons of war. The Algerian losses were 300.