士兵们在河对岸建立了桥头堡，为后续部队的推进做准备。

The soldiers secured a ___bridgehead on the opposite bank to prepare for further advances.

这家初创企业在欧洲市场站稳了脚跟，为未来扩张打下了基础。

The startup has established a ___bridgehead in the European market, laying the foundation for future expansion.