Al-‘Abbās ibn ‘Ali (born 4th Sha'aban|Sha‘bān 26 Islamic calendar|AH – 10 Muharram 61 AH; approximately May 15, 647 October 10, 680) was the son of Ali|‘Alī ibn Abī Tālib (first Shi'a Imam and fourth Rashidun|Rashidun Caliph) and Ummul Banin|Fātimah bint Hizam al-Kilabiyyah (commonly known as: Ummul Banīn – Mother of the Sons).
Al-‘Abbās is revered by Muslims for his loyalty to his half-brother Husayn ibn Ali|Husayn ibn ‘Alī, his respect for the Ahl al-Bayt, and his role in the Battle of Karbala|Battle of Karbalā. He was known as the greatest warrior in Arabia and mirrored the strength of his father, ‘Alī ibn Abī Tālib.
Abbas ibn Ali ibn Abu Talib was born on 4 Shaban 26 Hijra (Islam)|AH. He was the son of Ali ibn Abi Talib and Fatimah AlKilabiyya. Abbas had three brothers, Abdullah ibn Ali, Jafar ibn Ali, and Uthman ibn Ali. Abbas lived 34 years. Narratives state that he did not open his eyes after he was born until his brother Husayn ibn Ali took him in his arms.
Abbas married a distant cousin, Lubaba bint Ubaydillah. They had three sons, Fadl ibn Abbas|Fadl, Qasim ibn Abbas|Qasim, and Ubaydullah ibn al-Abbas|Ubaydullah.
Abbas's debut as a soldier was in the battle of Siffin. In 657 CE, Abbas's father Ali and Muawiyah I|Muawiya ibn Abi Sufyan, governor of Syria, were locked in a struggle for Islam. One of the main battles of this conflict was at Siffin, a place near the Euphrates river. During the course of the battle, Abbas entered the battlefield wearing the clothes of his father, who was known to be a deadly skilled warrior. Abbas killed many soldiers on the other side with his lightning swordsmanship. For this reason, Muawiya's soldiers mistook him for Ali because of his similar deadly art of war. However, Ali himself soon appeared on the battlefield. Muawiya's soldiers were astonished to see him, and were confused about who the other person was. Ali then introduced Abbas by saying, "He is Abbas, the Moon of the Hashimi family". He was trained by his Father Ali on the art of battle which is why he resembled his Father in the battlefield.
Abbas showed his loyalty to Husayn at the Battle of Karbala. After succeeding his father Muawiya ibn Abu Sufyan as Caliph, Yazid ibn Muawiyah required Husayn to pledge allegiance to him. Husayn refused to do so, saying: "I am the grandson of the messenger of Allah and Yazid is a drunkard, womanizer who is unfit for leadership. A person like me does not pay allegiance to a person like him". In 60 AH (680 CE), Husayn left Medina, with a small group of his companions and family, to travel to Kufa. The people of Kufa said that they would support Husayn if he claimed the Caliphate. On the way, Husayn and his group were intercepted. They were forced into a detour and arrived in Karbala on the 2nd of Muharram, 61 AH. Husayn's camp was surrounded and cut off from the Euphrates river. The camp ran out of water on the 7th of Muharram.
On 8 and 9 Muharram, Husayn refused to send Abbas to fight for water. Abbas was extremely eager to fight. Husayn asked Abbas to dig a well. Abbas and some of the Banu Hashim men began digging. But there was no success.
The Euphrates river was occupied by Yazid's Army to prevent the camp of Hussien from getting water. Shias believe that Abbas, because of his skill and bravery, could have attacked Yazid's army, occupied the river, and retrieved water for the camp alone. However, Abbas was not allowed to fight. He was only allowed to get water. Thus, he went to the river to get water for Husayn's 4 year old daughter Sakina bint Husayn. Sakina was very attached to Abbas, who was her uncle. To her, Abbas was the only hope for getting water. Abbas could not see her thirsty and crying "Al-Atash" (the thirst). When Abbas entered the battlefield, he only had a spear, and a bag for water in his hands. He was also given the authority to hold the standard (liwa') in the battle. Once he had made it to the river, he started filling the bag with water. Shias emphasize that Abbas's loyalty to Husayn was so great, that Abbas did not drink any water because he could not bear the thought that Sakina was thirsty (The essence of this event was to illustrate that Abbas conquered the Euphrates river, held it with his mighty hands, yet still did not drink. They claim that until this very day the water from Euphrates river circles the grave of Abbas) . After gathering the water, Abbas rode back towards the camp. On his way back, he was struck from behind and one of his arms was amputated. Then, he was stuck from behind again, amputating his other arm. Abbas was now carrying the water-bag in his mouth. The army of Yazid ibn Muawiyah started shooting arrows at him. One arrow hit the bag and water poured out of it. At that moment, Abbas lost all hope. One of Yazid's men hit his head with a mace and Abbas fell off his horse without the support of his arms. As he was falling, he called, "Ya Akkha" ("Oh master"). According to Shia tradition, Abbas fell first onto his face before he let the standard fall.
He was killed on Friday, 10 Muharram 61 Hijri on the banks of the river Euphrates). Hence, he is called Hero of Al-Qamah (another name for the river Euphrates). His death is generally mourned on the 8th night of Muharram. Shia Muslims mourn the death of all martyrs of Islam associated with Husayn in the month of Muharram, the first of the Islamic calendar, mainly in the first ten days (see Remembrance of Muharram). Fadl ibn Abbas and Qasim ibn Abbas also laid down their lives at Karbala. Ubaydullah ibn Abbas lived to continue the lineage of Abbas with five sons of his own.
‘Abbās was buried at that ground where he fell from his horse in Karbalā, Iraq. The Al Abbas Mosque|Al-‘Abbās Mosque was built around his grave, to which millions of pilgrims visit and pay homage every year.
Ghazi or Gha'Z (غازی) means "soldier who returns successfully from the battle". Although Abbas was killed at Karbala, he is known as Ghazi because, when he carried out the first strike against Yazid's army, his mission was to rescue the horse which was seized by Shimr during battle of Siffin. This horse belonged to his other half brother Hassan ibn Ali. Abbas retained control over the horse and presented it to Husayn. 
Abbas was given a horse named "Uqab" (Eagle). Shia claim that this horse was used by Muhammad and Ali and that this horse was presented to Muhammad by the King of Yemen, Saif ibn Zee Yazni, through Shaiba ibn Hashim|Abdul Muttalib. The king considered the horse to be very important and its superiority over other horses was evident by the fact that its genealogical tree was also maintained. It was initially named as "Murtajis". The name "Murtajis" comes from Arabic name "Rijis" which means thunder (lightning).