Why did Abu Bakr send armies into Syria?

Question

In this Hadith it is mentioned that Abu bakr RA sent armies into ash-Shaam:

Yahya related to me from Malik from Yahya ibn Said that Abu Bakr as-Siddiq was sending armies to ash-Sham. He went for a walk with Yazid ibn Abi Sufyan who was the commander of one of the battalions. It is claimed that Yazid said to Abu Bakr, "Will you ride or shall I get down?" Abu Bakrsaid, "I will not ride and you will not get down. I intend these steps of mine to be in the way of Allah." Then Abu Bakr advised Yazid, "You will find a people who claim to have totally given themselves to Allah. Leave them to what they claim to have given themselves. You will find a people who have shaved the middle of their heads, strike what they have shaved with the sword.
"I advise you ten things:
Do not kill women or children or an aged, infirm person. Do not cut down fruit-bearing trees. Do not destroy an inhabited place. Do not slaughter sheep or camels except for food. Do not burn bees and do not scatter them. Do not steal from the booty, and do not be cowardly."
[ Sunnah Ref: Muwatta Maalik 21/10 ]

Can someone tell me the name(s) of these wars in which Abu Bakr dispatched these armies to Syria and the reason for these wars?

Answer 1

Ibn Kathir writes in his history Al-Bidaya wa'l-Nihaya:

استهلت هذه السنة والصديق عازم على جمع الجنود ; ليبعثهم إلى الشام، وذلك بعد مرجعه من الحج، وذلك عملا بقوله تعالى: {يا أيها الذين آمنوا قاتلوا الذين يلونكم من الكفار وليجدوا فيكم غلظة واعلموا أن الله مع المتقين} [التوبة: 123] . وبقوله تعالى: {قاتلوا الذين لا يؤمنون بالله ولا باليوم الآخر} [التوبة: 29] الآية [التوبة: 29] . واقتداء برسول الله صلى الله عليه وسلم ; فإنه جمع المسلمين لغزو الشام وذلك عام تبوك، حتى وصلها في حر شديد وجهد، فرجع عامه ذلك، ثم بعث قبل مؤتة أسامة بن زيد مولاه ; ليغزو تخوم الشام، كما تقدم، ولما فرغ الصديق من أمر جزيرة العرب بسط يمينه إلى العراق، فبعث إليها خالد بن الوليد، ثم أراد أن يبعث إلى الشام ... ثم عقد لواء يزيد بن أبي سفيان ... خرج معه ماشيا يوصيه بما اعتمده في حربه ... قال محمد بن إسحاق، عن صالح بن كيسان: خرج أبو بكر ماشيا ويزيد بن أبي سفيان راكبا، فجعل يوصيه

[Events of the year 13 AH]:

In this year Abu Bakr resolved to gather the armies and to send them to Syria, and this was after he returned from Hajj. And this was action on the saying of Allah:

O you who have believed, fight those adjacent to you of the disbelievers and let them find in you harshness. And know that Allah is with the righteous.

^{— Quran 9:123}

And on His saying:

Fight those who do not believe in Allah or in the Last Day

^{— Quran 9:29}

And following the example of the Prophet ﷺ when he gathered the Muslims for an expedition into Syria and this was in the year of Tabuk, and when again before his death he sent an expedition under Usama bin Zaid to Syria.

Hence when Abu Bakr was free of the Arabian Peninsula he turned his attention towards Iraq and then towards Syria

... then Abu Bakr gave the banner to Yazid bin Abi Sufyan ... and walked with him and gave him advice on war ... Muhammad in Ishaq records: Abu Bakr was walking and Yazid bin Abi Sufyan was riding and Abu Bakr was giving him advise

As for the names of the battles fought in Syria, you can find them in any book of history.