With lots of hardships, our army finally broke through the enemy's first barrier.
Cantonese
由于敌方占据咗高地，我军陷入苦战。
由於敵方佔據咗高地，我軍陷入苦戰。
The enemy had taken the high ground and our army put up a struggle to fight back.
Examples (Wiktionary)
Mandarin
如果我们集中兵力在一个狭小的阵地上作消耗战的抵抗，将使我军失掉地理上和经济组织上的有利条件，犯阿比西尼亚的错误。
如果我們集中兵力在一個狹小的陣地上作消耗戰的抵抗，將使我軍失掉地理上和經濟組織上的有利條件，犯阿比西尼亞的錯誤。
rú guǒ wǒ men jí zhōng bīng lì zài yī ge xiá xiǎo de zhèn dì shàng zuò xiāo hào zhàn de dǐ kàng ， jiāng shǐ wǒ jūn shī diào dì lǐ shàng hé jīng jì zǔ zhī shàng de yǒu lì tiáo jiàn ， fàn ā bǐ xī ní yà de cuò wù ．
If we concentrate our forces on a narrow front for a defensive war of attrition, we would be throwing away the advantages of our geography and economic organization and repeating the mistake of Abyssinia.
Mandarin
就能大大地沮丧敌人的精神，振起我军的士气，号召世界的声援。
就能大大地沮喪敵人的精神，振起我軍的士氣，號召世界的聲援。
jiù néng dà dà de jǔ sàng dí rén de jīng shén ， zhèn qǐ wǒ jūn de shì qì ， hào zhào shì jiè de shēng yuán ．
It would greatly demoralize the enemy, stimulate the morale of our own forces and evoke international support.
Mandarin
将敌军对我军的战略上的分进合击，改为我军对敌军的战役或战斗上的分进合击。
將敵軍對我軍的戰略上的分進合擊，改為我軍對敵軍的戰役或戰鬥上的分進合擊。
jiāng dí jūn duì wǒ jūn de zhàn lüè shàng de fēn jìn hé jī ， gǎi wéi wǒ jūn duì dí jūn de zhàn yì huò zhàn dòu shàng de fēn jìn hé jī ．
We can change the converging attack directed by the enemy against us on the plane of strategy into converging attacks directed by us against the enemy on the plane of campaigns and battles.
Our army gave no consideration whatsoever to retreat, because it did not take account of either the partial or the total situation, and this was really rash and foolhardy conduct.