2:244 And fight in the cause of God and know that God is Hearing and Knowing.
2:245 Who is it that would loan God a goodly loan so He may multiply it for him many times over? And it is God who withholds and grants abundance, and to Him you will be returned.
2:246 Have you not considered the assembly of the Children of Israel after [the time of] Moses when they said to a prophet of theirs, “Send to us a king, and we will fight in the way of God”? He said, “Would you perhaps refrain from fighting if fighting was prescribed for you?” They said, “And why should we not fight in the cause of God when we have been driven out from our homes and from our children?” But when fighting was prescribed for them, they turned away, except for a few of them. And God is Knowing of the wrongdoers.
From chapter 2, verses 244 to 246 it recounts the story of the Israelites fleeing Egypt from Pharaoh, how they were poor and couldn’t fight back.
Some critics who want to portray Islam negatively only show 2:244, to show that ‘Jihad‘, mentioned in this verse is against innocents, which is not true. However, two verses down (Quran 2:246) it tells us why shouldn’t they fight since they have been driven from their homes and their children?
Furthermore, although the verses mention Moses and its people fleeing persecution, the verse could also refer to the Muslims who fled persecution from Makkah to Madinah, 1400 years ago. And having arrived in Madinah, they were still hounded, and attacked in their own city by the Quraysh. These events have been written about in detail, in the following article: ‘Did Quraysh Persecute Muslims When They Fled To Madinah?‘
“233 I.e., in a just war in self-defence against oppression or unprovoked aggression (cf. 2:190-194).” 
Maulana Muhammad Ali:
“243a. Ulaf is plural either of alf, meaning a thousand, or alif, a congregation or in a state of union (LL). The thousands referred to in this verse are the Israelites who left Egypt with Moses, the whole body of the Israelites being called a congregation in the Torah, and the clear mention of the Children of Israel after Moses in v. 246 corroborates this. Here we have a people who left their homes for fear of death, and besides the Israelites’ exodus from Egypt no incident in history answers to this description.
In fact, the very word kharaja (they went forth) from khuraj (meaning exodus) contains a direct hint to the exodus of the Israelites. But in one respect, the Holy Qur’an differs from the
Bible. According to the latter, the number of the Israelites was over 600,000 when they left Egypt (Num. 1:46), but the Qur’an says they were thousands, not hundreds of thousands.
There is no doubt, too, that the Israelites left Egypt for fear of death, for death would surely have been their fate if they had not emigrated. Not only were orders given by Pharaoh for their male offspring to be killed, but they were also kept in a state of bondage which would soon have brought them to a state of intellectual and moral death (compare v. 49).
The next incident in the history of that nation as referred to here is the Divine commandment to them, to “die”. This is more fully stated in 5:21–26. Moses told them to enter the Holy Land “which Allåh has ordained for you,” but they refused and were made to wander about in the wilderness for forty years, so that that generation perished.
This is also shown by their history as given in the Old Testament: “Your carcases shall fall in this wilderness … doubtless ye shall not come into the land” (Num. 14:29, 30).
This was their death. After that, we are told, Allah gave them life. This refers to the next generation, which was made to inherit the promised land: “But your little ones … they shall know the land which ye have despised” (Num. 14:31).
The whole is meant as a warning for the Muslims, who are told that if they followed the footsteps of the Israelites, death must be their fate. This warning is made clear in the next verse: And fight in the way of Allah.
244a. See 2:190; fighting in Allah’s way is equivalent to
fighting in defence of faith.” 
Marion Holmes Katz:
“…the passage beginning with verse 2:244, which follows a summons to battle with a narrative recounting the Israelites’ poor record of fighting in God’s cause.” References:
 The Message of The Quran translated and explained by Muhammad Asad, page 91
 The Holy Quran Arabic Text with English Translation, Commentary and comprehensive Introduction [Year 2002 Edition] by Maulana Muhammad Ali, page 110
 Body of Text: The Emergence of the Sunni Law of Ritual Purity [Copyright 2002] By Marion Holmes Katz, page 52