Then We gave back to you a return victory over them. And (17:6)

Almuntakhab Fi Tafsir Alquran Alkarim

When the conquerors abounded in self - conceit and you humbled yourselves to Allah We gave you mastery over them and We made you abound more in numerosity

Tafseer Tafheem-ul-Quran by Syed Abu-al-A'la Maududi

(17:6) Then after this We afforded you an opportunity to over-power them and helped you with abundance of riches and children and increased you far more in numbers than before. *8

Then We gave back to you a return victory over them. And meaning

*8) This refers to the lease of time that the Israelites (That is the people of Judah) got after their release from the captivity of Babylon. As for the people of Israel and Samaria, they did not rise again after their moral and spiritual degeneration. But among the people of Judah there still were some people who practised the truth and invited others also to follow it. They carried on their work of invitation to the truth among the remaining Israelites in Judah and exhorted those also to repent and follow the truth who had been driven out into Babylon and other lands. At last the mercy of AIIah came to their help. The downfall of Babylon started. The Persian king, Cyrus, took Babylon in 539 B.C.and in the following year issued a decree allowing the Israelites to return to and re-settle in their homeland. The Israelites began to return home in caravan after caravan, and ties continued for along time. Cyrus also allowed the Israelites to rebuild the Temple of Solomon but the neighbouring communities who had settled in this land resisted it. At last Darfius I appointed Zerubbabel, a grandson of the last king of Judah, governor of Judah in 522 B.C.who got the Temple rebuilt under the care of Prophet Haggai, Prophet Zechariah and Joshua. In 458 B.C. Ezra arrived in Judah along with an exiled group and the persian king Artaxerxes made the following decree.
"And thou, Ezra, after the wisdom of thy God that is in thine hand, set magistrates and judges, which may judge aII the people that are beyond the river, aII such as know the laws of thy God; and teach ye them that know them not.
And whosoever will not do the law of thy God and the law of the king let judgment be executed speedily upon him whether it be unto death, or to banishment, or to confiscation of goods, or to imprisonment. "(Ezra, 7:25-26).
Taking advantage of this decree, Ezra carried out the revival of the religion of Prophet Moses. He gathered together all the righteous and good people from the Israelites and set up a strong organisation. He compiled and spread the Pentateuch which contained the Torah, made arrangements for the religious education of the Israelites, enforced the law and started purging the people of moral and ideological weaknesses which the had adopted by intermixing with the other communities. He compelled they Jews to divorce the idolatrous wives they had married, and took a covenant from them that they would worship God alone and follow His Law only.
In 455 B.C.an exiled group came back to Judah under Nehemiah whom the Persian king appointed as the ruler of Jerusalem and ordered him to build the wall round the city. Thus, after 150 years the Holy city was fully restored and became the centre of Jewish religion and culture, But the Israelites of northern Palestine, and Samaria did not benefit by the work of revival done by Ezra.They built a rival sanctuary on Mount Gerizim, and tried to make it the religious centre for the people of the Book. This caused a further, and perhaps the final, split Between the Jews and the Samaritans.
The Jews suffered a set-back for a while with the fall of the Persian Empire and the conquests of Alexander the Great and the rise of the Greeks. After the death of Alexander, his kingdom was subdivided into three empires. Syria tell to the lot of the Seleucide empire, with Antioch as its capital, whose ruler Antiochus III incorporated Palestine into his dominions in 198 B.C. These Greek conquerors who were idolatrous by precept and freelance morally felt greatly ill at ease with the Jewish religion and culture. So, they began to propagate the rival Greek way of life and culture by political and economic pressure, and were able to win over a strong section of the Israelites who became their helpers. This external interference caused a split in the Jewish nation. One group among them readily adopted the Greek dress, the Greek language, the Greek way of life and the Greek sports, while the other persistently stuck to their own culture and way of life.
In 175 B.C. when Antiochus IV (who was called Epiphanes, that is, the manifestation of God) came to the throne, he used all his power and authority to stamp out the Jewish religion and culture. He got idols installed in the Holy Temple at Jerusalem and forced the Jews to prostrate themselves before them. He strictly forbade the rite of offering the sacrifices at the altar, and commanded the Jews to offer sacrifices to idolatrous deities instead. He proposed death penalty for those who would keep the Torah in their houses, or observe the Sabbath or perform circumcision of their children. But the Jews did not yield to this coercion, and started a powerful resistance movement, known in history as the revolt of the Maccabees. Though in this struggle the sympathies of the Greece-oriented Jews were with the Greeks, and they fully cooperated with the despots of Antioch to crush the Maccabean revolt, the common Jews who still retained the religious fervour of the days of Ezra sided with the Maccabees, who were ultimately able to drive out the Greeks and establish a free religious state which remained in power till 67 B.C This state prospered and in time extended to alI those territories which had once been under the control the kingdoms of Judah and Israel. It was able to annex a part of the land of the Philistines which had remained unconquered even in the days of Prophets David and Solomon (Peace be upon them).
This is the historical background of the verse of the Qur'an under commentary.
 

Then We gave back to you a return victory over them. And meaning in Urdu

اِس کے بعد ہم نے تمہیں اُن پر غلبے کا موقع دے دیا اور تمہیں مال اور اولاد سے مدد دی اور تمہاری تعداد پہلے سے بڑھا دی